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Morning sickness

Morning sickness, also called nausea, vomiting of pregnancy (emesis gravidarum or NVP), or pregnancy sickness, affects between 50[1] and 95 percent of all pregnant women as well as some women who use hormonal contraception or hormone replacement therapy. The nausea can be mild or induce actual vomiting. In extreme cases, known as hyperemesis gravidarum, hospitalization may be required to treat the resulting dehydration.


Duration of condition

Morning sickness can occur at any time of the day, though it occurs most often upon waking, because blood sugar levels are typically the lowest after a night without food.

Morning sickness usually starts in the first month of the pregnancy, peaking in the fifth to seventh weeks, and continuing until the 14th to 16th week. For half of the sufferers, it ends by the 16th week of pregnancy. It may take the others up to another month to get relief. Some women suffer intermittent episodes throughout their pregnancy.


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.
  • 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, which overstimulates normal nausea triggers.
  • An increase in bowel movement.

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.[2]

According to Margie Profet, eating vegetables may be a factor as well,[3] due to their small amount of toxins to deter insect infestation and while these toxins are normally harmless to adult humans, they are potentially dangerous to embryos.[4] However this theory 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".[5] Both Profet's vegetable theory and Deutsch's suggestion morning sickness's role is to reduce frequency of sexual intercourse, so preventing sexual uterine cramping that might be a cause spontaneous abortion,[6] have been rejected by a cross-cultural study that suggested 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".[7]

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.[4] In general, such theories are not accepted by modern scientists.


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, or ginger snaps.[8]
  • Vitamin B6 (either pyridoxine or pyridoxamine), often taken in combination with the antihistamine doxylamine (Diclectin).
  • Lemons, particularly the smelling of freshly cut lemons.
  • Accommodating food cravings and aversions.
  • Eating dry crackers in the morning.
  • Trying the BRATT diet: bananas, rice, applesauce, toast and tea.[9]
  • Drinking liquids 30 to 45 minutes after eating solid food.

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.[10]

Thalidomide tragedy

Further information: Thalidomide#History

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.


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,[11] although the researchers noted that their survey was not conclusive.[12]

Associations with miscarriage risk

Studies have shown that women who suffer from morning sickness are less likely to have miscarriages as well as less likely to give birth to a baby with birth defects.[4] 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.[citation needed] It is also mentioned that many women having a molar pregnancy or an ectopic pregnancy suffer strong nausea.


  1. ^ American Pregnancy Association. Morning Sickness. Retrieved on 2007-04-08.
  2. ^ Pepper GV, Craig Roberts S (2006). "Rates of nausea and vomiting in pregnancy and dietary characteristics across populations". Proc. Biol. Sci. 273 (1601): 2675–9. doi:10.1098/rspb.2006.3633. PMID 17002954. “Rates of nausea and vomiting in pregnancy were correlated with high intake of macronutrients (kilocalories, protein, fat, carbohydrate), as well as sugars, stimulants, meat, milk and eggs, and with low intake of cereals and pulses... However, factor analysis of dietary components revealed one factor significantly associated with NVP rate, which was characterized by low cereal consumption and high intake of sugars, oilcrops, alcohol and meat. The results provide further evidence for an association between diet and NVP prevalence across populations, and support for the idea that NVP serves an adaptive prophylactic function against potentially harmful foodstuffs.”
  3. ^ Profet, Margie. (1992) Pregnancy sickness as adaptation: a deterrent to maternal ingestion of teratogens.
  4. ^ a b c Pinker, Steven (1997). How the Mind Works. New York: W. W. Norton & Company, Inc.. ISBN 0-393-31848-6. 
  5. ^ Brown JE, Kahn ES, Hartman TJ (1997). "Profet, profits, and proof: do nausea and vomiting of early pregnancy protect women from "harmful" vegetables?". Am. J. Obstet. Gynecol. 176 (1 Pt 1): 179–81. PMID 9024110.
  6. ^ Deutsch JA (1994). "Pregnancy sickness as an adaptation to concealed ovulation". Riv. Biol. 87 (2-3): 277–95. PMID 7701232.
  7. ^ Flaxman SM, Sherman PW (2000). "Morning sickness: a mechanism for protecting mother and embryo". The Quarterly review of biology 75 (2): 113–48. PMID 10858967.
  8. ^ Borrelli F, Capasso R, Aviello G, Pittler MH, Izzo AA (2005). "Effectiveness and safety of ginger in the treatment of pregnancy-induced nausea and vomiting". Obstetrics and gynecology 105 (4): 849–56. doi:10.1097/01.AOG.0000154890.47642.23. PMID 15802416.
  9. ^ Warhus, Susan. Tips to ease pregnancy's morning sickness. Retrieved on 2007-03-05.
  10. ^ British National Formulary (March 2003). "4.6 Drugs used in nausea and vertigo - Vomiting of pregnancy", "BNF", 45. 
  11. ^ Westfall RE, Janssen PA, Lucas P, Capler R (2006). "Survey of medicinal cannabis use among childbearing women: patterns of its use in pregnancy and retroactive self-assessment of its efficacy against 'morning sickness'". Complementary therapies in clinical practice 12 (1): 27–33. doi:10.1016/j.ctcp.2005.09.006. PMID 16401527.
  12. ^ Tom Blackwell. "More pregnancy highs than lows", National Post, 2006-01-17. Retrieved on 2006-06-07. 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Morning_sickness". A list of authors is available in Wikipedia.
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