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Morning sickness
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Morning sickness, also called nausea gravidarum, nausea, vomiting of pregnancy (emesis gravidarum or NVP), or pregnancy sickness is a condition that affects more than half of all pregnant women, as well as some women who use hormonal contraception or hormone replacement therapy. Usually, it is present in the early hours of the morning and reduces as the day progresses. The nausea can be mild or induce actual vomiting.
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Encyclopedia
Morning sickness, also called nausea gravidarum, nausea, vomiting of pregnancy (emesis gravidarum or NVP), or pregnancy sickness is a condition that affects more than half of all pregnant women, as well as some women who use hormonal contraception or hormone replacement therapy. Usually, it is present in the early hours of the morning and reduces as the day progresses. The nausea can be mild or induce actual vomiting. In extreme cases, vomiting may be severe enough to cause dehydration, weight loss, acidosis and hypokalemia. This condition is known as hyperemesis gravidarum and occurs in about 1% of all pregnancies. Nausea and vomiting can be one of the first signs of pregnancy and usually begins around the 6th week of pregnancy. It can occur at any time of the day, and for most women it seems to stop around the 12th week of pregnancy.
Causes
There is insufficient evidence to find a single (or multiple) cause, but the leading theories for proximate causes include:
- An increase in the circulating level of the hormone estrogen. Estrogen levels may increase by up to a hundredfold during pregnancy. However, there is no consistent evidence of differences in estrogen levels between women who experience sickness and those who don't.
- Low blood sugar (hypoglycemia) due to the placenta draining energy from the mother, though studies have not confirmed this.
- An increase in progesterone relaxes the muscles in the uterus, which prevents early childbirth, but may also relax the stomach and intestines, leading to excess stomach acids and gastroesophageal reflux disease.
- An increase in human chorionic gonadotropin.
- An increase in sensitivity to odors, which overstimulates normal nausea triggers.
- An increase in bowel movement.
- The body's effort to detoxify thoroughly for the health of the developing embryo. This is supported by evidence that the liver and kidneys become more active than usual at the start of a pregnancy.
As for root causes, this issue is still somewhat controversial. A notable current scientific hypothesis is that morning sickness exists as a safeguard for the embryo's health. Biologists Gillian V. Pepper and S. Craig Roberts have done a study that indicates that the intake of alcohol, sugar, oils, and meat can trigger morning sickness. This then acts as a way of discouraging ingestion of less healthy foods.
According to Margie Profet, eating vegetables might be a factor as well, due to their small amount of toxins to deter insect infestation; while these toxins are normally harmless to adult humans, they are potentially dangerous to embryos. However, this idea has been rejected by a prospective, population-based study which concluded that "claims made in the popular press about food and health relationships should be evaluated by the media as fiction unless supported by scientific research". Both Profet's vegetable theory and Deutsch's suggestion that the role of morning sickness is to reduce frequency of sexual intercourse, so preventing sexual uterine cramping that might cause spontaneous abortion, have been rejected by a cross-cultural study. This study suggested that morning sickness is more frequently observed in societies that have animal products as dietary staples which may "be dangerous to pregnant women and their embryos because they often contain parasites and pathogens" and hence "that morning sickness serves an adaptive, prophylactic function".
Many other non-scientific theories for morning sickness have been proposed in the past. Notably, according to psychologist Sigmund Freud, morning sickness is the result of the mother's loathing of her husband. The subconscious manifestation of this is a desire to abort the fetus through vomiting. In general, such theories are not accepted by modern scientists.
Treatments
Treatments for morning sickness typically aim to lessen the symptoms of nausea, rather than attacking the root cause(s) of the nausea. Treatments include:
- Lemons, particularly the smelling of freshly cut lemons.
- Avoiding an empty stomach.
- Accommodating food cravings and aversions.
- Eating five or six small meals per day, rather than three large ones.
- Eating cabbage.
- Trying the BRAT diet: bananas, rice, applesauce, toast and tea.
- Ginger, in capsules, tea, ginger ale, or ginger snaps.
- Eating dry crackers in the morning.
- Drinking liquids 30 to 45 minutes after eating solid food.
- If liquids are vomited, sucking ice cubes made from water or fruit juice.
- Vitamin B6 (either pyridoxine or pyridoxamine), often taken in combination with the antihistamine doxylamine (Diclectin).
A doctor may prescribe anti-nausea medications if the expectant mother suffers from dehydration or malnutrition as a result of her morning sickness, a condition known as hyperemesis gravidarum. In the US, Zofran (ondansetron) is the usual drug of choice, though the high cost is prohibitive for some women; in the UK, older drugs with which there is a greater experience of use in pregnancy are preferred, with first choice being promethazine otherwise as second choice metoclopramide, or prochlorperazine.
Thalidomide
Thalidomide was originally developed and prescribed as a cure for morning sickness in West Germany, but its use was discontinued when the drug's teratogenic properties came to light. The United States Food and Drug Administration never approved thalidomide for use as a cure for morning sickness.
Associations with miscarriage risk
Studies have shown that women who suffer from morning sickness are less likely to have miscarriages or to give birth to a baby with birth defects. Other doctors disagree with these links and claim that the mother's sensitivity to the changes in her body is not a variable that indicates risk of miscarriage. It is also mentioned that many women having a molar pregnancy or an ectopic pregnancy suffer strong nausea.
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