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Morning sickness

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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. Related to increased estrogen levels, a similar form of nausea is also seen in some women who use hormonal contraception or hormone replacement therapy. Sometimes 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, however, not severe enough to cause metabolic derangement. In more severe cases, vomiting may cause dehydration, weight loss, alkalosis 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 (counting gestational age from 14 days before conception). In spite of its common name, it can occur at any time of the day, and for most women it may stop around the 12th week of pregnancy.

Causes

Proximate causes of pregnancy sickness include:

  • An increase in the circulating level of the hormone estrogen. Estrogen levels may increase by up to a hundredfold during pregnancy.[1][unreliable source] However, there is no consistent evidence of differences in estrogen levels and levels of bilirubin between women that experience sickness and those that do not.[2]
  • Low blood sugar (hypoglycemia) due to the placenta's draining energy from the mother, though studies have not confirmed this.[3]
  • 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. It is probably not the human chorionic gonadotropin itself that causes the nausea. More likely, it is the human chorionic gonadotropin-stimulating the maternal ovaries to secrete estrogen, which in turn causes the nausea.[4]
  • An increase in sensitivity to odors, which overstimulates normal nausea triggers.
  • An increase in bilirubin levels due to increased liver enzymes.

Note that Gastroesophageal reflux disease can also be caused by pregnancy, and may result in nausea and vomiting.

Morning sickness as a defense mechanism

Morning sickness is currently believed to be an evolved trait that protects the fetus against toxins ingested by the mother.[5] [6] Many plants contain chemical toxins that serve as a deterrent to being eaten. Adult humans, like other animals, have defenses against plant toxins, including extensive arrays of detoxification enzymes manufactured by the liver and the surface tissues of various other organs. In the fetus, these defenses are not yet fully developed, and even small doses of plant toxins that have negligible effects on the adult can be harmful or lethal to the embryo.[7] Pregnancy sickness causes women to experience nausea when exposed to the smell or taste of foods that are likely to contain toxins injurious to the fetus, even though they may be harmless to her.

There is considerable evidence in support of this theory, including:[8] [9]

  • Morning sickness is very common among pregnant women, which argues in favor of its being a functional adaptation and against the idea that it is a pathology.
  • Fetal vulnerability to toxins peaks at around 3 months, which is also the time of peak susceptibility to morning sickness.
  • There is a good correlation between toxin concentrations in foods, and the tastes and odors that cause revulsion.

Women who have no morning sickness are more likely to miscarry.[10] This may because such women are more likely to ingest substances that are harmful to the fetus.[11]

In addition to protecting the fetus, morning sickness may also protect the mother. Pregnant women's immune systems are suppressed during pregnancy, it is presumed to reduce the chances of rejecting tissues of their own offspring.[12] Because of this, animal products containing parasites and harmful bacteria can be especially dangerous to pregnant women. There is evidence that morning sickness is often triggered by animal products including meat and fish.[13]

If morning sickness is a defense mechanism against the ingestion of toxins, the prescribing of anti-nausea medication to pregnant women may have the undesired side effect of causing birth defects or miscarriages by encouraging harmful dietary choices.[8] On the other hand, many domestic vegetables have been purposely bred to have lower levels of toxins than in the distant past, and so the level of threat to the embryo may not be as high as it was when the defense mechanism first evolved.[14]

Treatments

There is no evidence to demonstrate the effectiveness of treatments for morning sickness.[15] Suggested treatments typically aim to lessen the symptoms of nausea, rather than attacking the root cause(s) of the nausea. Frequently suggested treatments include:

  • If the vomiting/nausea is due to acid reflux, taking an antacid or two before bed may help reduce the stomach acid and prevent morning vomiting.
  • If the vomiting/nausea is due to reduced stomach motility then reducing fibre and fat intake may help. (For example, white bread instead of brown bread, well cooked fruits and vegetables instead of raw, avoiding high-fiber foods, removing skins from fruit or vegetables, avoiding fatty meats and high-fat foods.) Also, walking after meals may help to increase stomach motility.
  • If the vomiting/nausea is due to acid reflux or reduced stomach motility, eating more small meals during the day (instead of several larger ones) may help. This will also help to keep blood sugar levels more consistent.
  • If the vomiting/nausea is due to iron pills (or multivitamins containing iron) a slower-release form or several lower-dose iron pills may help.
  • If the vomiting/nausea is due to low blood sugar, avoiding an empty stomach may help (e.g. snacking throughout the day with several smaller meals instead of a few large ones.)
  • Folk remedy: Lemons, in particular the smelling of freshly cut lemons.
  • Accommodating food cravings and aversions.
  • Eating cabbage.[16]
  • Ginger, in capsules, tea, ginger ale, or ginger snaps.[17][18][19] Safety concerns have been raised in the medical community due to the powerful pharmacological activity of ginger, especially its anticoagulant action.[20][21]
  • Eating dry crackers in the morning. Some women benefit from eating crackers before rising out of bed in the morning. This may be because it helps to absorb the stomach acid.
  • Drinking liquids 30 to 45 minutes after eating solid food.
  • If liquids are vomited, sucking ice cubes made from water or fruit juice or trying lollipops.
  • Wearing acupressure wristbands to stimulate the "Nei-Kuan" acupuncture point on your wrist. [22][23][24][25][26]

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.[27] When all other treatments fail, doctors may consider trying a corticosteroid medication such as methylprednisolone.[28] This medication can be given orally or intravenously. It should not be used before 10 weeks gestation because of a small risk that it could cause a cleft lip or palate in the fetus. Because of possible maternal complications, the medicine should not be used for longer than six weeks.

Thalidomide

Further information: Thalidomide

Thalidomide was originally developed and prescribed as a cure for morning sickness in West Germany, but its use was discontinued when it was found to cause birth defects. The United States Food and Drug Administration never approved thalidomide for use as a cure for morning sickness.

References

  • Morning Sickness: A Comprehensive Guide to the Causes and Treatments, Nicky Wesson, Vermilion (1997), ISBN 0-09-181538-X

Notes

  1. ^ "First Trimester Pregnancy". The Visible Embryo. Retrieved 2008-07-06.
  2. ^ n Elizabeth Bauchner; Wendy Marquez. "Morning Sickness: Coping With The Worst". NY Metro Parents Magazine. Retrieved 2008-07-06.
  3. ^ Erick, Miriam (2004). Managing Morning Sickness: A Survival Guide for Pregnant Women. Bull Publishing Company. ISBN 0-923521-82-8. Retrieved 2008-07-06.
  4. ^ Niebyl, Jennifer R. (2010). "Nausea and Vomiting in Pregnancy". New England Journal of Medicine. 363 (16): 1544–1550. doi:10.1056/NEJMcp1003896. PMID 20942670.
  5. ^ Hook, E. B. (1976). "Changes in tobacco smoking and ingestion of alcohol and caffeinated beverages during early pregnancy: are these consequences, in part, of feto-protective mechanisms diminishing maternal exposure to embryotoxins?". In Kelly, S. (ed.). Birth Defects: Risks and Consequences. Academic Press. pp. 173–181.
  6. ^ Profet, Margie (1992). "Pregnancy Sickness as Adaptation: A Deterrent to Maternal Ingestion of Teratogens". In Barkow, Jerome; Cosmides; Tooby, Leda (eds.). The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Oxford University Press. pp. 327–365. {{cite book}}: More than one of |editor1-first= and |editor-first= specified (help)
  7. ^ Beck, F. (1973). Human Embryology and Genetics. Blackwell Scientific.
  8. ^ a b Nesse, Randolphe M; Williams, George C (1996). Why We Get Sick (First ed.). New York: Vintage Books. p. 290. {{cite book}}: Cite has empty unknown parameters: |origmonth=, |chapterurl=, and |month= (help)
  9. ^ Pepper, GV; Roberts, Gillian V. (2006). "Rates of nausea and vomiting in pregnancy and dietary characteristics across populations". Proceedings of the Royal Society B. 273 (1601): 2675–2679. doi:10.1098/rsbp.2006.3633. PMC 1635459. PMID 17002954. {{cite journal}}: |first3= missing |last3= (help)
  10. ^ Chan, Ronna L.; Olshan, A. F.; Savitz, D. A.; Herring, A. H.; Daniels, J. L.; Peterson, H. B.; Martin, S. L.; et al. (Sept. 22, 2010). "Severity and duration of nausea and vomiting symptoms in pregnancy and spontaneous abortion". Human Reproduction. 25 (11): 2907–12. doi:10.1093/humrep/deq260. PMC 3140259. PMID 20861299. {{cite journal}}: Check date values in: |date= (help); Explicit use of et al. in: |first= (help)
  11. ^ Sherman, Paul W.; Flaxman, Samuel M. (2002). "Nausea and vomiting of pregnancy in an evolutionary perspective". Am J Obstet Gynecol. 186 (5): S190–S197. doi:10.1067/mob.2002.122593. PMID 12011885.
  12. ^ Haig, David (October 1993). "Genetic conflicts in human pregnancy". Quarterly Review of Biology. 68 (4): 495–532. doi:10.1086/418300. PMID 8115596.
  13. ^ Flaxman, Samuel M.; Sherman, Paul W. (June 2000). "Morning sickness: a mechanism for protecting mother and embryo". Quarterly Review of Biology. 75 (2): 113–148. doi:10.1086/393377. PMID 10858967.
  14. ^ Martin, Mike (June 29, 2009). "Margie Profet's Unfinished Symphony". Weekly Scientist.
  15. ^ Matthews A, Dowswell T, Haas DM, Doyle M, O'Mathúna DP (2010). Matthews, Anne (ed.). "Interventions for nausea and vomiting in early pregnancy". Cochrane Database of Systematic Reviews. 2010 (9): CD007575. doi:10.1002/14651858.CD007575.pub2. PMID 20824863.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ^ Akhtar MS, Munir M (1989). "Evaluation of the gastric anti-ulcerogenic effects of Solanum nigrum, Brassica oleracea and Ocimum basilicum in rats". Journal of Ethnopharmacology. 27 (1–2): 163–176. doi:10.1016/0378-8741(89)90088-3. PMID 2515396. Brassica oleracea (leaf) powder did not affect the ulcer index significantly but its aqueous extract lowered the index and increased hexosamine levels, suggesting gastric mucosal protection.
  17. ^ Ensiyeh, Jenabi (2009). "Comparing ginger and vitamin B6 for the treatment of nausea and vomiting in pregnancy: a randomised controlled trial". Midwifery. 25 (6): 649–653. doi:10.1016/j.midw.2007.10.013. {{cite journal}}: Unknown parameter |month= ignored (help)
  18. ^ "Morning sickness: Lifestyle and home remedies". Mayo Foundation for Medical Education and Research. 2008. Retrieved 2012-03-28.
  19. ^ "Pregnancy Guide: Morning sickness". University of Maryland Medical Center. Retrieved 2012-03-28.
  20. ^ 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ Tiran, Denise (2012). "Ginger to reduce nausea and vomiting during pregnancy: Evidence of effectiveness is not the same as proof of safety". Complementary Therapies in Clinical Practice. 18 (1): 22. doi:10.1016/j.ctcp.2011.08.007. ISSN 1744-3881. {{cite journal}}: Unknown parameter |month= ignored (help)
  22. ^ Werntoft E, Dykes AK. Effect of acupressure on nausea and vomiting during pregnancy. A randomized, placebo-controlled pilot study. Journal of Reproductive Medicine, 2001 46(9):835-9 September
  23. ^ Steele NM, French J, Gatherer-Boyles J, Newman S, Leclaire S. Effect of acupressure by Sea-Bands on nausea and vomiting of pregnancy. Journal of Obstetric, Gynecologic and Neonatal Nursing 2001 Jan-Feb;30(1):61-70
  24. ^ Smith C, Crowther C, Beilby J. Acupuncture to treat nausea and vomiting in early pregnancy: a randomized controlled trial. Birth March 2002; 29(1):1-9
  25. ^ Smith C, Crowther C, Beilby J. Pregnancy outcome following women’s participation in a randomised controlled trial of acupuncture to treat nausea and vomiting in early pregnancy.
  26. ^ Complementary Therapies in Medicine 2002 June;10(2):78-83
  27. ^ British National Formulary (2003). "4.6 Drugs used in nausea and vertigo - Vomiting of pregnancy". BNF (45 ed.). ISBN 0-85369-416-8. {{cite book}}: Unknown parameter |month= ignored (help)
  28. ^ American College of Obstetricians and Gynecologists. Nausea and Vomiting of Pregnancy. ACOG Practice Bulletin Number 52, April 2004. Reaffirmed 2009.
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