Prenatal cocaine exposure
Encyclopedia
Prenatal cocaine exposure (PCE) occurs when a pregnant woman uses cocaine
and thereby exposes her fetus
to the drug
. Crack baby was a term coined to describe children who were exposed to crack
(cocaine in smokable form) as fetuses; the concept of the crack baby emerged in the US during the 1980s and 90s in the midst of a great deal of media surrounding crack. Early studies reported that people who had been exposed to crack in utero would be severely emotionally, mentally, and physically disabled; this belief became common in the scientific and lay communities. Fears were widespread that a generation of crack babies were going to put severe strain on society and social services as they grew up. Later studies failed to substantiate the findings of earlier ones that PCE has severe disabling consequences; these earlier studies had been methodologically flawed (e.g. with small sample size
s and confounding factors). Scientists have come to understand that the findings of the early studies were vastly overstated and that most people who were exposed to cocaine in utero are normal.
No specific disorders or conditions have been found to result for people whose mothers used cocaine while pregnant. Studies focusing on children of six years and younger have not shown any direct, long-term effects of PCE on language, growth, or development as measured by test scores. PCE also appears to have little effect on infant growth.
However, PCE is associated with premature birth
, birth defects, attention deficit disorder, and other conditions. Cognitive, motor, behavior, developmental, and language problems also appear to result from PCE.
The effects of cocaine on a fetus are thought to be similar to those of tobacco and less severe than those of alcohol. No scientific evidence has shown a difference in harm to a fetus of crack and powder cocaine.
PCE is very difficult to study because it very rarely occurs in isolation: usually it coexists with a variety of other factors, which may confound a study's results. For example, pregnant mothers who use cocaine often use other drugs in addition to cocaine, or they may be malnourished and lacking in medical care. Children in households where cocaine is abused are at risk of violence and neglect, and those in foster care may experience problems due to unstable family situations. Thus researchers have had difficulty in determining which effects result from PCE and which result from other factors in the children's histories.
of the 1980s and 90s in the US, fear existed throughout the country that PCE would create a generation of youth with severe behavioral and cognitive problems. Early studies in the mid-1980s reported that cocaine use in pregnancy caused children to have severe problems including cognitive, developmental, and emotional disruption. These early studies had methodological problems including small sample size
, confounding factors like poor nutrition
, and use of other drugs by the mothers. However, the results of the studies sparked widespread media discussion in the context of the new War on Drugs
. For example a 1985 study that showed harmful effects of cocaine use during pregnancy created a huge media buzz. The term "crack baby" resulted from the publicity surrounding crack and PCE.
It was common in media reports of the phenomenon to emphasize that babies exposed to crack in utero would never develop normally. The children were reported to be inevitably destined to be physically and mentally disabled for their whole lives.
Babies exposed to crack in utero were written off as doomed to be severely disabled, and many were abandoned in hospitals. Experts foresaw the development of a "biological underclass" of born criminals who would prey on the rest of the population. Crime rates were predicted to rise when the generation of crack-exposed infants grew up (instead they dropped). It was predicted that the children would be difficult to console, irritable, and hyperactive, putting a strain on the school system. Charles Krauthammer, a columnist from The Washington Post
wrote in 1989, "[t]heirs will be a life of certain suffering, of probable deviance, of permanent inferiority." The president of Boston University at the time, John Silber, said "crack babies ... won't ever achieve the intellectual development to have consciousness of God."
At the time, the proposed mechanism by which cocaine harmed fetuses was as a stimulant—it was predicted that cocaine would disrupt normal development of parts of the brain that dealt with stimulation, resulting in problems like bipolar disorder
and attention deficit disorder. Reports from the mid 1980s to early 90s raised concerns about links between PCE and slowed growth, deformed limbs, defects of the kidneys and genitourinary
and gastrointestinal tract
s, neurological damage, small head size
, atrophy
or cysts in the cerebral cortex
, bleeding into the brain's ventricles
, obstruction of blood supply in the central nervous system
. Studies that find that exposure has significant effects may be more likely to be published than those that do not, a factor that may have biased reporting on the effects of PCE toward indicating more severe outcomes as the crack epidemic emerged. Between 1980 and 1989, 57% of studies showing cocaine has effects on a fetus were accepted by the Society for Pediatric Research, compared with only 11% of studies showing no cocaine effects.
After the early studies which reported that PCE children would be severely disabled came studies that purported to show that cocaine exposure in utero has no important effects. Almost every prenatal complication originally thought to be due directly to PCE was found to result from confounding factors such as poor maternal nutrition, use of other drugs, depression, and lack of prenatal care
. More recently the scientific community has begun to reach an understanding that PCE does have some important effects but that they are not severe as was predicted in the early studies. Most people who were exposed to cocaine in utero are normal. The effects of PCE are subtle but they exist.
Cocaine, a small molecule, is able to cross the placenta
into the bloodstream of the fetus. In fact it may be present in a higher concentration in the amniotic fluid
than it is in the mother's bloodstream. The skin of the fetus is able to absorb the chemical directly from the amniotic fluid until the 24th week of pregnancy. Cocaine can also show up in breast milk
and affect the nursing baby.
Cocaine prevents the reuptake
of neurotransmitters such as norepinepherine and epinepherine, so they stay in the synapse
longer, causing excitement of the sympathetic nervous system
and evoking a stress response. The euphoria
experienced by cocaine users is thought to be largely due to the way it prevents the neurotransmitter serotonin
from being reabsorbed by the presynaptic neuron which released it.
Use of cocaine during pregnancy can negatively affect both the mother and the fetus. But the ways in which cocaine affects a fetus are poorly understood. There are multiple mechanisms by which cocaine exposure harms a fetus: it causes constriction (narrowing) of blood vessels
and changes in brain chemistry
, and it may alter expression of certain gene
s. Cocaine affects neurotransmitter
s that are involved in the development of the fetus's brain. Cocaine may affect fetal development directly by altering the development of the monoaminergic system in the brain. In studies with rats, cocaine has been shown to cause apoptosis
(programmed cell death) in fetuses; this could be a mechanism for some of the abnormalities of the heart associated with PCE.
The ways in which cocaine affects a fetus are poorly understood, but one possibility is that it harms the fetus in part by interfering with blood supply to the uterus. The reduction in blood flow to the uterus limits the delivery of oxygen and nutrients to the fetus. The reduced blood flow to the uterus may also play a role in congenital malformations and slowed fetal growth. For example, it may be this reduction in blood flow that leads to gut damage in the infant. Cocaine causes changes in the mother's blood pressure
that are thought to be the cause of stroke
s in the fetus; one study found that 6% of cocaine-exposed infants had had one or more strokes. Such prenatal strokes may be the cause of neurological problems found in some cocaine-exposed infants after birth.
Blood vessel contraction can also cause premature labor and birth. Cocaine has also been found to enhance the contractility of the tissue in the uterus
, another factor that has been suggested as a possible mechanism for its contribution to increased prematurity rates. Increased contractility of the uterus may also be behind the increased likelihood of placental abruption
(the placenta tearing away from the uterine wall) which some findings have linked with PCE.
(the infant's earliest stool). Hair analysis, however, can give false positives for cocaine exposure. The mother's urine can also be tested for drugs.
, insensitive parenting, and maternal depression. Some studies have found PCE-related differences in height and weight while others have not; these differences are generally gone or small by the time children are school-age. When researchers are able to identify effects that result from PCE, these effects are typically small.
Some effects of PCE have been demonstrated with high exposures to cocaine but not with low ones.
Studies have found that children exposed to cocaine during fetal development experience problems with language, behavior, development, and attention.
Some, but not all, PCE children experience hypertonia
(excessive muscle tone
), problems with attention, or delays in brain growth or language. However, systematic reviews have found that after controlling for other factors that could be misleading, there is no evidence that fetal crack exposure causes problems different from those caused by other risk factors to which those fetuses are exposed.
As many as 17–27% of cocaine-using pregnant women deliver prematurely. There are also data showing that spontaneous abortion and low birth weight
are associated with cocaine use. The increased risk of placental abruption
with cocaine use has been well documented. Using cocaine while pregnant also heightens the chances of maternal and fetal vitamin deficiencies, respiratory distress syndrome
for the baby, and infarction
of the bowels.
Early reports found that cocaine-exposed babies were at high risk for sudden infant death syndrome
. However, by itself, cocaine exposure during fetal development has not subsequently been identified as a risk factor for the syndrome.
While newborns who were exposed prenatally to drugs such as barbiturates or heroin frequently have symptoms of drug withdrawal
(neonatal abstinence syndrome
), this does not happen with babies exposed to crack in utero; at least, such symptoms are difficult to separate in the context of other factors such as prematurity or prenatal exposure to other drugs.
Unlike fetal alcohol syndrome
, no set of characteristics has been discovered that results uniquely from cocaine exposure in utero. Much is still not known about what factors may exist to aid children who were exposed to cocaine in utero.
Cocaine causes impaired growth of the fetus's brain, an effect that is most pronounced with high levels of cocaine and prolonged duration of exposure throughout all three trimesters of pregnancy. Those PCE children who had slowed brain growth as fetuses are at higher risk for impaired brain growth and motor, language and attention problems after they are born.
Cognitive and attention skills can be impacted by PCE, possibly due to effects on brain areas such as the prefrontal cortex
. Children whose mothers used cocaine during pregnancy may develop symptoms akin to those of attention deficit disorder. Language development has also been found in some studies to be impacted by PCE, but language studies have failed to reliably show a detriment caused by in utero cocaine exposure.
Evidence suggests that in utero cocaine exposure leads to problems with behavior and sustained attention
, possibly by affecting parts of the brain that are vulnerable to toxin
s during fetal development. The changes in behavior and attention caused by PCE are measurable by standardized scales; however these behavioral effects seem to be mild.
s in cocaine-exposed babies younger than seven months (but not older); however, this finding could be attributed to a failure to control for in utero tobacco exposure.
A review of the literature reported that cocaine use causes congenital defects between 15 and 20% of the time; however another large-scale study found no difference in rates of birth anomalies in PCE and non-PCE infants. Most PCE-related congenital defects are found in the brain, heart, genitourinary tract, arms and legs. Abnormalities in the development of the heart both before and after birth have been linked to PCE; the mechanism by which this occurs is poorly understood. Heart malformations can include a missing ventricle
and defects with the septum
of the heart, and can result in potentially deadly congestive heart failure
. Cocaine use by pregnant mothers may directly or indirectly contribute to defects in the formation of the circulatory system
and is associated with abnormalities in development of the aorta
. Genital malformations occur at a higher-than-normal rate with PCE. The liver and lungs are also at higher risk for abnormalities. Cloverleaf skull, a congenital malformation in which the skull
has three lobes, the brain is deformed, and hydrocephalus
occurs, is also associated with PCE.
It is not well understood why cocaine exposure is associated with congenital malformations. It has been suggested that some of these birth defects could be due to cocaine's disruption of blood vessel growth.
An estimated 0.5 to 3% of pregnant women worldwide use cocaine.
In some parts of North America, the rate of cocaine use by pregnant women is as much as 10–45%. In the US, almost 90% of women who abuse drugs are of childbearing age. A 1995 survey in the US found that between 30,000 and 160,000 cases of prenatal exposure to cocaine occur each year. By one estimate, in the US 100,000 babies are born each year after having been exposed to crack cocaine in utero. Pregnant women in urban parts of the US and who are of a low socioeconomic status
use cocaine more often. However, the real prevalence
of cocaine use by pregnant women is unknown.
, homicide
, and distribution of drugs to a minor; however these approaches have generally been rejected in the courts on the basis that a fetus is not legally a child. Between 1985 and 2001, more than 200 women in over 30 US states faced prosecution for drug use during pregnancy. In South Carolina, a woman who used crack in her third trimester of pregnancy was sentenced to prison for eight years when her child was born with cocaine metabolite
s in its system. The Supreme Court of South Carolina upheld this conviction. From 1989 to 1994, in the midst of public outcry about cocaine babies, the Medical University of South Carolina tested pregnant women for cocaine, reporting those who tested positive to the police. The US Supreme Court
found the policy to be unacceptable on constitutional
grounds in 2001.
Some advocates argue that punishment for crack-using pregnant women as a means to treat their addiction is a violation of their right to privacy. According to studies, fear of prosecution and having children taken away is associated with a refusal to seek prenatal care or medical treatment.
Some nonprofit organizations aim to prevent PCE with birth control
. One such initiative, Project Prevention
, offers crack-addicted women money as an incentive to undergo long-term birth control or, frequently, sterilization—an approach which has brought it under fire for eugenics
.
is more harmful than the PCE. Teachers may expect these children to be disruptive and developmentally delayed
. Children who were exposed to cocaine may be teased by others who know of the exposure, and problems these children have may be misdiagnosed by doctors or others as resulting from PCE when they may really be due to factors like illness or abuse.
The social stigma of the drug also complicates studies of PCE; researchers labor under the awareness that their findings will have political implications. In addition, the perceived hopelessness of 'crack babies' may cause researchers to ignore possibilities for early intervention that could help them. The social stigma may turn out to be a self-fulfilling prophecy
.
, alcohol
, or marijuana) or to the environment in which the child is raised. Some effects (such as head circumference
, body weight
, and height) that appear in studies to result from prenatal cocaine exposure disappear when studies control for prenatal exposure to other drugs.
PCE is very difficult to study because of a variety of factors that may confound the results: pre- and postnatal care may be poor; the pregnant mother and child may be malnourished
; the amount of cocaine a mother takes can vary; she may take a variety of drugs during pregnancy in addition to cocaine; measurements for detecting deficits may not be sensitive enough; and results that are found may only last a short time. PCE is clustered with other risk factors to the child such as maltreatment, domestic violence
, and prenatal exposure to other substances. Such environmental factors are known to adversely affect children in the same areas being studied with respect to PCE. Most women who use cocaine while pregnant use other drugs too. Addiction to any substance, including crack, may be a risk factor for child abuse or neglect
. Crack addiction, like other addictions, distracts parents from the child and leads to inattentive parenting. Many drug users do not get prenatal care
, for a variety of reasons including that they may not know they are pregnant. Many crack addicts get no medical care at all and have extremely poor diets, and children who around crack smoking are at risk of inhaling secondary smoke. Cocaine using mothers also have a higher rate of to sexually transmitted infections such as HIV
and hepatitis
. Drug use by mothers puts children at high risk for environmental problems, and PCE does not present much risk beyond these risk factors that occur alongside it. In some cases, it is not clear whether direct results of PCE lead to behavioral problems, or whether environmental factors are at fault. For examples, it may be that children who have caregiver instability have more behavioral problems as a result, or it may be that behavioral problems manifested by PCE children lead to greater turnover in caregivers. Other factors that make studying PCE difficult include high rates of attrition (loss of participants) from studies, unwillingness of mothers to tell the truth about drug history, and uncertainty of dosages of street drugs.
The difficulties in isolating crack exposure and other difficulties with studies mean that although many effects previously thought to have been attributable to crack exposure in utero have not been found, undiscovered effects may emerge as pressures on children grow as they reach school age and puberty.
Cocaine
Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...
and thereby exposes her fetus
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
to the drug
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
. Crack baby was a term coined to describe children who were exposed to crack
Crack cocaine
Crack cocaine is the freebase form of cocaine that can be smoked. It may also be termed rock, hard, iron, cavvy, base, or just crack; it is the most addictive form of cocaine. Crack rocks offer a short but intense high to smokers...
(cocaine in smokable form) as fetuses; the concept of the crack baby emerged in the US during the 1980s and 90s in the midst of a great deal of media surrounding crack. Early studies reported that people who had been exposed to crack in utero would be severely emotionally, mentally, and physically disabled; this belief became common in the scientific and lay communities. Fears were widespread that a generation of crack babies were going to put severe strain on society and social services as they grew up. Later studies failed to substantiate the findings of earlier ones that PCE has severe disabling consequences; these earlier studies had been methodologically flawed (e.g. with small sample size
Sample size
Sample size determination is the act of choosing the number of observations to include in a statistical sample. The sample size is an important feature of any empirical study in which the goal is to make inferences about a population from a sample...
s and confounding factors). Scientists have come to understand that the findings of the early studies were vastly overstated and that most people who were exposed to cocaine in utero are normal.
No specific disorders or conditions have been found to result for people whose mothers used cocaine while pregnant. Studies focusing on children of six years and younger have not shown any direct, long-term effects of PCE on language, growth, or development as measured by test scores. PCE also appears to have little effect on infant growth.
However, PCE is associated with premature birth
Premature birth
In humans preterm birth refers to the birth of a baby of less than 37 weeks gestational age. The cause for preterm birth is in many situations elusive and unknown; many factors appear to be associated with the development of preterm birth, making the reduction of preterm birth a challenging...
, birth defects, attention deficit disorder, and other conditions. Cognitive, motor, behavior, developmental, and language problems also appear to result from PCE.
The effects of cocaine on a fetus are thought to be similar to those of tobacco and less severe than those of alcohol. No scientific evidence has shown a difference in harm to a fetus of crack and powder cocaine.
PCE is very difficult to study because it very rarely occurs in isolation: usually it coexists with a variety of other factors, which may confound a study's results. For example, pregnant mothers who use cocaine often use other drugs in addition to cocaine, or they may be malnourished and lacking in medical care. Children in households where cocaine is abused are at risk of violence and neglect, and those in foster care may experience problems due to unstable family situations. Thus researchers have had difficulty in determining which effects result from PCE and which result from other factors in the children's histories.
Historical context
During the crack epidemicCrack Epidemic
The United States crack epidemic refers to the surge of crack houses and crack cocaine use in major cities in the United States between 1984 and 1990...
of the 1980s and 90s in the US, fear existed throughout the country that PCE would create a generation of youth with severe behavioral and cognitive problems. Early studies in the mid-1980s reported that cocaine use in pregnancy caused children to have severe problems including cognitive, developmental, and emotional disruption. These early studies had methodological problems including small sample size
Sample size
Sample size determination is the act of choosing the number of observations to include in a statistical sample. The sample size is an important feature of any empirical study in which the goal is to make inferences about a population from a sample...
, confounding factors like poor nutrition
Nutrition
Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
, and use of other drugs by the mothers. However, the results of the studies sparked widespread media discussion in the context of the new War on Drugs
War on Drugs
The War on Drugs is a campaign of prohibition and foreign military aid and military intervention being undertaken by the United States government, with the assistance of participating countries, intended to both define and reduce the illegal drug trade...
. For example a 1985 study that showed harmful effects of cocaine use during pregnancy created a huge media buzz. The term "crack baby" resulted from the publicity surrounding crack and PCE.
It was common in media reports of the phenomenon to emphasize that babies exposed to crack in utero would never develop normally. The children were reported to be inevitably destined to be physically and mentally disabled for their whole lives.
Babies exposed to crack in utero were written off as doomed to be severely disabled, and many were abandoned in hospitals. Experts foresaw the development of a "biological underclass" of born criminals who would prey on the rest of the population. Crime rates were predicted to rise when the generation of crack-exposed infants grew up (instead they dropped). It was predicted that the children would be difficult to console, irritable, and hyperactive, putting a strain on the school system. Charles Krauthammer, a columnist from The Washington Post
The Washington Post
The Washington Post is Washington, D.C.'s largest newspaper and its oldest still-existing paper, founded in 1877. Located in the capital of the United States, The Post has a particular emphasis on national politics. D.C., Maryland, and Virginia editions are printed for daily circulation...
wrote in 1989, "[t]heirs will be a life of certain suffering, of probable deviance, of permanent inferiority." The president of Boston University at the time, John Silber, said "crack babies ... won't ever achieve the intellectual development to have consciousness of God."
At the time, the proposed mechanism by which cocaine harmed fetuses was as a stimulant—it was predicted that cocaine would disrupt normal development of parts of the brain that dealt with stimulation, resulting in problems like bipolar disorder
Bipolar disorder
Bipolar disorder or bipolar affective disorder, historically known as manic–depressive disorder, is a psychiatric diagnosis that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated energy levels, cognition, and mood with or without one or...
and attention deficit disorder. Reports from the mid 1980s to early 90s raised concerns about links between PCE and slowed growth, deformed limbs, defects of the kidneys and genitourinary
Genitourinary system
In anatomy, the genitourinary system or urogenital system is the organ system of the reproductive organs and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways, like the male urethra...
and gastrointestinal tract
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
s, neurological damage, small head size
Microcephaly
Microcephaly is a neurodevelopmental disorder in which the circumference of the head is more than two standard deviations smaller than average for the person's age and sex. Microcephaly may be congenital or it may develop in the first few years of life...
, atrophy
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...
or cysts in the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
, bleeding into the brain's ventricles
Intraventricular hemorrhage
An intraventricular hemorrhage , often abbreviated "IVH," is a bleeding into the brain's ventricular system, where the cerebrospinal fluid is produced and circulates through towards the subarachnoid space...
, obstruction of blood supply in the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
. Studies that find that exposure has significant effects may be more likely to be published than those that do not, a factor that may have biased reporting on the effects of PCE toward indicating more severe outcomes as the crack epidemic emerged. Between 1980 and 1989, 57% of studies showing cocaine has effects on a fetus were accepted by the Society for Pediatric Research, compared with only 11% of studies showing no cocaine effects.
After the early studies which reported that PCE children would be severely disabled came studies that purported to show that cocaine exposure in utero has no important effects. Almost every prenatal complication originally thought to be due directly to PCE was found to result from confounding factors such as poor maternal nutrition, use of other drugs, depression, and lack of prenatal care
Prenatal care
Prenatal care refers to the medical and nursing care recommended for women before and during pregnancy. The aim of good prenatal care is to detect any potential problems early, to prevent them if possible , and to direct the woman to appropriate specialists, hospitals, etc...
. More recently the scientific community has begun to reach an understanding that PCE does have some important effects but that they are not severe as was predicted in the early studies. Most people who were exposed to cocaine in utero are normal. The effects of PCE are subtle but they exist.
Pathophysiology
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
into the bloodstream of the fetus. In fact it may be present in a higher concentration in the amniotic fluid
Amniotic fluid
Amniotic fluid or liquor amnii is the nourishing and protecting liquid contained by the amniotic sac of a pregnant woman.- Development of amniotic fluid :...
than it is in the mother's bloodstream. The skin of the fetus is able to absorb the chemical directly from the amniotic fluid until the 24th week of pregnancy. Cocaine can also show up in breast milk
Breast milk
Breast milk, more specifically human milk, is the milk produced by the breasts of a human female for her infant offspring...
and affect the nursing baby.
Cocaine prevents the reuptake
Reuptake
Reuptake, or re-uptake, is the reabsorption of a neurotransmitter by a neurotransmitter transporter of a pre-synaptic neuron after it has performed its function of transmitting a neural impulse....
of neurotransmitters such as norepinepherine and epinepherine, so they stay in the synapse
Synapse
In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell...
longer, causing excitement of the sympathetic nervous system
Sympathetic nervous system
The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's nervous system fight-or-flight response...
and evoking a stress response. The euphoria
Euphoria
Euphoria is an emotional and mental state defined as a sense of great elation and well being.Euphoria may also refer to:* Euphoria , a genus of scarab beetles* Euphoria, a genus name previously used for the longan and other trees...
experienced by cocaine users is thought to be largely due to the way it prevents the neurotransmitter serotonin
Serotonin
Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
from being reabsorbed by the presynaptic neuron which released it.
Use of cocaine during pregnancy can negatively affect both the mother and the fetus. But the ways in which cocaine affects a fetus are poorly understood. There are multiple mechanisms by which cocaine exposure harms a fetus: it causes constriction (narrowing) of blood vessels
Vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
and changes in brain chemistry
Neurochemistry
Neurochemistry is the specific study of neurochemicals, which include neurotransmitters and other molecules such as neuro-active drugs that influence neuron function. This principle closely examines the manner in which these neurochemicals influence the network of neural operation...
, and it may alter expression of certain gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s. Cocaine affects neurotransmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
s that are involved in the development of the fetus's brain. Cocaine may affect fetal development directly by altering the development of the monoaminergic system in the brain. In studies with rats, cocaine has been shown to cause apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
(programmed cell death) in fetuses; this could be a mechanism for some of the abnormalities of the heart associated with PCE.
The ways in which cocaine affects a fetus are poorly understood, but one possibility is that it harms the fetus in part by interfering with blood supply to the uterus. The reduction in blood flow to the uterus limits the delivery of oxygen and nutrients to the fetus. The reduced blood flow to the uterus may also play a role in congenital malformations and slowed fetal growth. For example, it may be this reduction in blood flow that leads to gut damage in the infant. Cocaine causes changes in the mother's blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
that are thought to be the cause of stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
s in the fetus; one study found that 6% of cocaine-exposed infants had had one or more strokes. Such prenatal strokes may be the cause of neurological problems found in some cocaine-exposed infants after birth.
Blood vessel contraction can also cause premature labor and birth. Cocaine has also been found to enhance the contractility of the tissue in the uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
, another factor that has been suggested as a possible mechanism for its contribution to increased prematurity rates. Increased contractility of the uterus may also be behind the increased likelihood of placental abruption
Placental abruption
Placental abruption is a complication of pregnancy, wherein the placental lining has separated from the uterus of the mother. It is the most common pathological cause of late pregnancy bleeding. In humans, it refers to the abnormal separation after 20 weeks of gestation and prior to birth...
(the placenta tearing away from the uterine wall) which some findings have linked with PCE.
Diagnosis
Cocaine use during pregnancy can be discovered by asking the mother, but sometimes women will not admit to having used drugs; this "maternal interview" method has been found to be less reliable for discovering cocaine use than for other drugs such as marijuana. More reliable methods for detecting cocaine exposure involve testing the newborn's hair or meconiumMeconium
Meconium is the earliest stools of an infant. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the uterus: intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile, and water. Meconium is almost sterile, unlike later feces, is viscous and...
(the infant's earliest stool). Hair analysis, however, can give false positives for cocaine exposure. The mother's urine can also be tested for drugs.
Effects and prognosis
Drug use in the first trimester is the most harmful to the fetus in terms of neurological and developmental outcome. The effects of PCE later in a child's life are poorly understood; there is little information about the effects of in utero cocaine exposure on children over age five. Cocaine exposure in utero may affect the structure and function of the brain, predisposing children to developmental problems later, or these effects may be explained by children of crack-using mothers being at higher risk for domestic violenceDomestic violence
Domestic violence, also known as domestic abuse, spousal abuse, battering, family violence, and intimate partner violence , is broadly defined as a pattern of abusive behaviors by one or both partners in an intimate relationship such as marriage, dating, family, or cohabitation...
, insensitive parenting, and maternal depression. Some studies have found PCE-related differences in height and weight while others have not; these differences are generally gone or small by the time children are school-age. When researchers are able to identify effects that result from PCE, these effects are typically small.
Some effects of PCE have been demonstrated with high exposures to cocaine but not with low ones.
Studies have found that children exposed to cocaine during fetal development experience problems with language, behavior, development, and attention.
Some, but not all, PCE children experience hypertonia
Hypertonia
Hypertonia a condition marked by an abnormal increase in muscle tension and a reduced ability of a muscle to stretch. It is caused by lesions to upper motor neurons in the central nervous system, which carry information from the central nervous system to the muscles and control posture, muscle...
(excessive muscle tone
Muscle tone
In physiology, medicine, and anatomy, muscle tone is the continuous and passive partial contraction of the muscles, or the muscle’s resistance to passive stretch during resting state. It helps maintain posture, and it declines during REM sleep.-Purpose:Unconscious nerve impulses maintain the...
), problems with attention, or delays in brain growth or language. However, systematic reviews have found that after controlling for other factors that could be misleading, there is no evidence that fetal crack exposure causes problems different from those caused by other risk factors to which those fetuses are exposed.
As many as 17–27% of cocaine-using pregnant women deliver prematurely. There are also data showing that spontaneous abortion and low birth weight
Low birth weight
Low birth weight is defined as a birth weight of a liveborn infant of less than 2,500 g. regardless of gestational age-Causes:LBW is either the result of preterm birth or of the infant being small for gestational age , or a combination of...
are associated with cocaine use. The increased risk of placental abruption
Placental abruption
Placental abruption is a complication of pregnancy, wherein the placental lining has separated from the uterus of the mother. It is the most common pathological cause of late pregnancy bleeding. In humans, it refers to the abnormal separation after 20 weeks of gestation and prior to birth...
with cocaine use has been well documented. Using cocaine while pregnant also heightens the chances of maternal and fetal vitamin deficiencies, respiratory distress syndrome
Infant respiratory distress syndrome
Infant respiratory distress syndrome , also called neonatal respiratory distress syndrome or respiratory distress syndrome of newborn, previously called hyaline membrane disease, is a syndrome in premature infants caused by developmental insufficiency of surfactant production and structural...
for the baby, and infarction
Infarction
In medicine, infarction refers to tissue death that is caused by a local lack of oxygen due to obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct.-Causes:...
of the bowels.
Early reports found that cocaine-exposed babies were at high risk for sudden infant death syndrome
Sudden infant death syndrome
Sudden infant death syndrome is marked by the sudden death of an infant that is unexpected by medical history, and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation. An infant is at the highest risk for SIDS during sleep, which is why it is sometimes...
. However, by itself, cocaine exposure during fetal development has not subsequently been identified as a risk factor for the syndrome.
While newborns who were exposed prenatally to drugs such as barbiturates or heroin frequently have symptoms of drug withdrawal
Withdrawal
Withdrawal can refer to any sort of separation, but is most commonly used to describe the group of symptoms that occurs upon the abrupt discontinuation/separation or a decrease in dosage of the intake of medications, recreational drugs, and alcohol...
(neonatal abstinence syndrome
Neonatal withdrawal
Neonatal withdrawal or neonatal abstinence syndrome is a withdrawal syndrome of infants, caused by administration of drugs. Tolerance, dependence and withdrawal may occur as a result of repeated administration of drugs, or even after short-term high dose use for example during mechanical...
), this does not happen with babies exposed to crack in utero; at least, such symptoms are difficult to separate in the context of other factors such as prematurity or prenatal exposure to other drugs.
Unlike fetal alcohol syndrome
Fetal alcohol syndrome
Fetal alcohol syndrome is a pattern of mental and physical defects that can develop in a fetus in association with high levels of alcohol consumption during pregnancy. Current research also implicates other lifestyle choices made by the prospective mother...
, no set of characteristics has been discovered that results uniquely from cocaine exposure in utero. Much is still not known about what factors may exist to aid children who were exposed to cocaine in utero.
Mental, emotional, and behavioral outcomes
Little evidence suggests a link between fetal cocaine exposure and problems with cognitive development. In IQ studies, cocaine-exposed children score no lower than others, and children exposed to marijuana and alcohol in utero were at the same level as those who were exposed to those drugs in addition to cocaine. In school-age and younger children, PCE does not appear in studies to predispose children to poorer intellectual performance. However, results of studies aiming to measure mental performance have been mixed, with some reporting measurable deficits in cocaine-exposed babies and others showing no differences between cocaine-exposed and control groups. Studies of developmental delays have also been mixed.Cocaine causes impaired growth of the fetus's brain, an effect that is most pronounced with high levels of cocaine and prolonged duration of exposure throughout all three trimesters of pregnancy. Those PCE children who had slowed brain growth as fetuses are at higher risk for impaired brain growth and motor, language and attention problems after they are born.
Cognitive and attention skills can be impacted by PCE, possibly due to effects on brain areas such as the prefrontal cortex
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
. Children whose mothers used cocaine during pregnancy may develop symptoms akin to those of attention deficit disorder. Language development has also been found in some studies to be impacted by PCE, but language studies have failed to reliably show a detriment caused by in utero cocaine exposure.
Evidence suggests that in utero cocaine exposure leads to problems with behavior and sustained attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
, possibly by affecting parts of the brain that are vulnerable to toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s during fetal development. The changes in behavior and attention caused by PCE are measurable by standardized scales; however these behavioral effects seem to be mild.
Physical outcomes
PCE may interfere with the way the motor system matures. Reports on whether PCE affects motor functioning are mixed, with some reporting measurable deficits and others reporting none. Some, but not all, studies have found impairments in development of motor skillMotor skill
A motor skill is a learned sequence of movements that combine to produce a smooth, efficient action in order to master a particular task. The development of motor skill occurs in the motor cortex, the region of the cerebral cortex that controls voluntary muscle groups.- Development of motor skills...
s in cocaine-exposed babies younger than seven months (but not older); however, this finding could be attributed to a failure to control for in utero tobacco exposure.
A review of the literature reported that cocaine use causes congenital defects between 15 and 20% of the time; however another large-scale study found no difference in rates of birth anomalies in PCE and non-PCE infants. Most PCE-related congenital defects are found in the brain, heart, genitourinary tract, arms and legs. Abnormalities in the development of the heart both before and after birth have been linked to PCE; the mechanism by which this occurs is poorly understood. Heart malformations can include a missing ventricle
Ventricle (heart)
In the heart, a ventricle is one of two large chambers that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs. The Atria primes the Pump...
and defects with the septum
Septum
In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...
of the heart, and can result in potentially deadly congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
. Cocaine use by pregnant mothers may directly or indirectly contribute to defects in the formation of the circulatory system
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
and is associated with abnormalities in development of the aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
. Genital malformations occur at a higher-than-normal rate with PCE. The liver and lungs are also at higher risk for abnormalities. Cloverleaf skull, a congenital malformation in which the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
has three lobes, the brain is deformed, and hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
occurs, is also associated with PCE.
It is not well understood why cocaine exposure is associated with congenital malformations. It has been suggested that some of these birth defects could be due to cocaine's disruption of blood vessel growth.
Epidemiology
In some parts of North America, the rate of cocaine use by pregnant women is as much as 10–45%. In the US, almost 90% of women who abuse drugs are of childbearing age. A 1995 survey in the US found that between 30,000 and 160,000 cases of prenatal exposure to cocaine occur each year. By one estimate, in the US 100,000 babies are born each year after having been exposed to crack cocaine in utero. Pregnant women in urban parts of the US and who are of a low socioeconomic status
Socioeconomic status
Socioeconomic status is an economic and sociological combined total measure of a person's work experience and of an individual's or family’s economic and social position in relation to others, based on income, education, and occupation...
use cocaine more often. However, the real prevalence
Prevalence
In epidemiology, the prevalence of a health-related state in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population...
of cocaine use by pregnant women is unknown.
Legal and ethical issues
The harm to a child from PCE has implications for public policy and law. Some US states have pressed charges against pregnant women who use drugs, including child abuseChild abuse
Child abuse is the physical, sexual, emotional mistreatment, or neglect of a child. In the United States, the Centers for Disease Control and Prevention and the Department of Children And Families define child maltreatment as any act or series of acts of commission or omission by a parent or...
, homicide
Homicide
Homicide refers to the act of a human killing another human. Murder, for example, is a type of homicide. It can also describe a person who has committed such an act, though this use is rare in modern English...
, and distribution of drugs to a minor; however these approaches have generally been rejected in the courts on the basis that a fetus is not legally a child. Between 1985 and 2001, more than 200 women in over 30 US states faced prosecution for drug use during pregnancy. In South Carolina, a woman who used crack in her third trimester of pregnancy was sentenced to prison for eight years when her child was born with cocaine metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...
s in its system. The Supreme Court of South Carolina upheld this conviction. From 1989 to 1994, in the midst of public outcry about cocaine babies, the Medical University of South Carolina tested pregnant women for cocaine, reporting those who tested positive to the police. The US Supreme Court
Supreme Court of the United States
The Supreme Court of the United States is the highest court in the United States. It has ultimate appellate jurisdiction over all state and federal courts, and original jurisdiction over a small range of cases...
found the policy to be unacceptable on constitutional
United States Constitution
The Constitution of the United States is the supreme law of the United States of America. It is the framework for the organization of the United States government and for the relationship of the federal government with the states, citizens, and all people within the United States.The first three...
grounds in 2001.
Some advocates argue that punishment for crack-using pregnant women as a means to treat their addiction is a violation of their right to privacy. According to studies, fear of prosecution and having children taken away is associated with a refusal to seek prenatal care or medical treatment.
Some nonprofit organizations aim to prevent PCE with birth control
Birth control
Birth control is an umbrella term for several techniques and methods used to prevent fertilization or to interrupt pregnancy at various stages. Birth control techniques and methods include contraception , contragestion and abortion...
. One such initiative, Project Prevention
Project Prevention
Project Prevention is an American non-profit organization that pays drug addicts cash for volunteering for long-term birth control, including sterilization. Originally based in California and now based in North Carolina, the organization began operating in the United Kingdom in 2010...
, offers crack-addicted women money as an incentive to undergo long-term birth control or, frequently, sterilization—an approach which has brought it under fire for eugenics
Eugenics
Eugenics is the "applied science or the bio-social movement which advocates the use of practices aimed at improving the genetic composition of a population", usually referring to human populations. The origins of the concept of eugenics began with certain interpretations of Mendelian inheritance,...
.
Social stigma
Children who were exposed to crack prenatally face social stigma as babies and school-aged children; some experts say that the "crack baby" social stigmaSocial stigma
Social stigma is the severe disapproval of or discontent with a person on the grounds of characteristics that distinguish them from other members of a society.Almost all stigma is based on a person differing from social or cultural norms...
is more harmful than the PCE. Teachers may expect these children to be disruptive and developmentally delayed
Developmental disability
Developmental disability is a term used in the United States and Canada to describe lifelong disabilities attributable to mental or physical impairments, manifested prior to age 18. It is not synonymous with "developmental delay" which is often a consequence of a temporary illness or trauma during...
. Children who were exposed to cocaine may be teased by others who know of the exposure, and problems these children have may be misdiagnosed by doctors or others as resulting from PCE when they may really be due to factors like illness or abuse.
The social stigma of the drug also complicates studies of PCE; researchers labor under the awareness that their findings will have political implications. In addition, the perceived hopelessness of 'crack babies' may cause researchers to ignore possibilities for early intervention that could help them. The social stigma may turn out to be a self-fulfilling prophecy
Self-fulfilling prophecy
A self-fulfilling prophecy is a prediction that directly or indirectly causes itself to become true, by the very terms of the prophecy itself, due to positive feedback between belief and behavior. Although examples of such prophecies can be found in literature as far back as ancient Greece and...
.
Research
A number of the effects that had been thought after early studies to be attributable to prenatal exposure to cocaine are actually due partially or wholly to other factors, such as exposure to other substances (including tobaccoTobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...
, alcohol
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...
, or marijuana) or to the environment in which the child is raised. Some effects (such as head circumference
Circumference
The circumference is the distance around a closed curve. Circumference is a special perimeter.-Circumference of a circle:The circumference of a circle is the length around it....
, body weight
Body weight
The term body weight is used in daily English speech as well as in the contexts of biological and medical sciences to describe the mass of an organism's body. Body weight is measured in kilograms throughout the world, although in some countries it is still measured in pounds or stones and pounds...
, and height) that appear in studies to result from prenatal cocaine exposure disappear when studies control for prenatal exposure to other drugs.
PCE is very difficult to study because of a variety of factors that may confound the results: pre- and postnatal care may be poor; the pregnant mother and child may be malnourished
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
; the amount of cocaine a mother takes can vary; she may take a variety of drugs during pregnancy in addition to cocaine; measurements for detecting deficits may not be sensitive enough; and results that are found may only last a short time. PCE is clustered with other risk factors to the child such as maltreatment, domestic violence
Domestic violence
Domestic violence, also known as domestic abuse, spousal abuse, battering, family violence, and intimate partner violence , is broadly defined as a pattern of abusive behaviors by one or both partners in an intimate relationship such as marriage, dating, family, or cohabitation...
, and prenatal exposure to other substances. Such environmental factors are known to adversely affect children in the same areas being studied with respect to PCE. Most women who use cocaine while pregnant use other drugs too. Addiction to any substance, including crack, may be a risk factor for child abuse or neglect
Child neglect
Child neglect is defined as:# "the failure of a person responsible for a child’s care and upbringing to safeguard the child’s emotional and physical health and general well-being"...
. Crack addiction, like other addictions, distracts parents from the child and leads to inattentive parenting. Many drug users do not get prenatal care
Prenatal care
Prenatal care refers to the medical and nursing care recommended for women before and during pregnancy. The aim of good prenatal care is to detect any potential problems early, to prevent them if possible , and to direct the woman to appropriate specialists, hospitals, etc...
, for a variety of reasons including that they may not know they are pregnant. Many crack addicts get no medical care at all and have extremely poor diets, and children who around crack smoking are at risk of inhaling secondary smoke. Cocaine using mothers also have a higher rate of to sexually transmitted infections such as HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
and hepatitis
Hepatitis
Hepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...
. Drug use by mothers puts children at high risk for environmental problems, and PCE does not present much risk beyond these risk factors that occur alongside it. In some cases, it is not clear whether direct results of PCE lead to behavioral problems, or whether environmental factors are at fault. For examples, it may be that children who have caregiver instability have more behavioral problems as a result, or it may be that behavioral problems manifested by PCE children lead to greater turnover in caregivers. Other factors that make studying PCE difficult include high rates of attrition (loss of participants) from studies, unwillingness of mothers to tell the truth about drug history, and uncertainty of dosages of street drugs.
The difficulties in isolating crack exposure and other difficulties with studies mean that although many effects previously thought to have been attributable to crack exposure in utero have not been found, undiscovered effects may emerge as pressures on children grow as they reach school age and puberty.