Morning sickness, also called nausea and vomiting of pregnancy (NVP), or pregnancy sickness, affects between 50 and 95 percent of all pregnant women. It is also sometimes experienced by women who take birth control pills or hormone replacement therapy. The amount of nausea can vary from mild amounts to
actual vomiting. In extreme cases, known as hyperemesis gravidarum, hospital admission may be required to correct the resulting dehydration.
When it occurs
Morning sickness is not confined to the
morning: nausea can occur at any time of the day, though it most commonly occurs soon after waking, perhaps because the stomach is empty at that time.
Morning sickness usually starts in the first month of the pregnancy, peaking in the 5th to 7th weeks, and continuing until the 14th to 16th week. For 50% of all sufferers, it ends by the 16th week of pregnancy. For the other half, it may take up to another month to get relief but some women will have morning sickness off and on for their entire pregnancy.
Causes
There is insufficient evidence to pin down a single (or multiple) cause, but the leading theories include:
- An increase in the circulating level of the hormone estrogen. Estrogen levels may increase by up to a hundredfold during pregnancy.
- Low blood sugar during pregnancy.
- 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.
- An increase in human chorionic gonadotropin.
- An increase in sensitivity to odors.
- Eating vegetables. Vegetables produce a small amount of toxins to deter insect infestation and while these toxins are normally harmless to humans, they are potentially dangerous to embryos. One theory suggests that becoming nauseated during pregnancy is an evolutionary measure to prevent a mother from eating vegetables, thereby protecting the embryo from the toxins. Other studies, however, have linked consumption of fruits and vegetables to higher birth weights, which tend to mean healthier babies.
- Intake of alcohol, sugar, oils and meat, which have been postulated to cause a natural trigger of morning sickness in the body as a way of discouraging ingestion of less healthy foods.
[Gillian V. Pepper and S. Craig Roberts "Rates of nausea and vomiting in pregnancy and dietary characteristics across populations" from Proceedings of The Royal Society]
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:
- Avoiding an empty stomach
- Eating five or six small meals per day, rather than three large ones
- Ginger, in capsules, tea, ginger ale, ginger beer or ginger snaps; but avoid large or frequent doses of Ginger. Ginger has been known to cause birth defects.
[Borrelli, Francesca et al. "Effectiveness and Safety of Ginger in the Treatment of Pregnancy-Induced Nausea and Vomiting," Obstetrics & Gynecology. September 1, 2005; 106(3): 640 - 641.]
- Vitamin B6 (either pyridoxine or pyridoxamine) sometimes taken in combination with the antihistamine doxylamine
- Acupressure applied to the P6 point on the inside of the forearm, one-sixth of the way from the wrist to the elbow
- Lemons, particularly the smelling of freshly cut lemons
- Fulfilling food cravings
A doctor may prescribe anti-nausea medications if the expectant mother suffers from dehydration or malnutrition as a result of her morning sickness. 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 tragedy
Thalidomide was originally developed and prescribed as a cure for morning sickness in Great Britain, 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.
Research
A recent Canadian survey conducted by researchers at the
University of British Columbia and the
University of Victoria suggested that the use of medical marijuana may be effective in combating morning sickness,
although the researchers noted that their survey was not conclusive.
Associations with miscarriage risk
Studies have shown that women who suffer from morning sickness are less likely to have
miscarriages, while other studies have shown that the majority of women who do miscarry had multiple pregnancy symptoms including pregnancy sickness. Some doctors refute the claim that lack of morning sickness indicates an increased risk of miscarriage. They claim 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.
External links
Schwangerschaftserbrechen
Notes
Obstetrics