The Morning sickness reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Morning sickness

Morning sickness (also called "nausea and vomiting of pregnancy," or "NVP") affects between 50 and 85 percent of all pregnant women. It is not confined to the morning: nausea can occur at any time of the day. The cause is not known, and there are a number of theories to explain it:

• An increase in the hormone progesterone relaxes the muscles in the uterus, which prevents early pregancy labor, but may also relax the stomach and intestines, leading to excess stomach acids.
• An increase in hCG (human chorionic gonadotropin).
• An increase in sensitivity to odors.
• Eating vegetables. One theory is that the small amounts of toxins vegetables produce to deter insect infestation are normally harmless to humans but extremely dangerous to embryos; therefore, becoming nauseous during pregnancy was an evolutionary measure to protect the embryo. Other studies however have linked consumption of fruits and vegetables to higher birth weights (higher birth weights tend to mean healthier babies).

For 50% of all sufferers, it ends by the 16th week of pregnancy. Studies have shown that women who suffer from NVP are less likely to have miscarriages.

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