Morning sickness, also called nausea and vomiting of pregnancy (NVP), nausea gravidarum, emesis gravidarum, andpregnancy sickness, is a pregnancy discomfort that affects more than half of all pregnant women.
Symptoms may be present early in the morning and reduce as the day progresses. However, in spite of its common name, nausea and vomiting of pregnancy can occur at any time during the day. For most women the sickness ends around the 12th week of pregnancy (the end of the first trimester).
Related to increased estrogen levels, a similar form of nausea is also seen in some women who use hormonal contraception orhormone replacement therapy. The nausea can be mild or induce actual vomiting. In more severe cases, vomiting may causedehydration, weight loss, high blood pH, and a low level of potassium in the blood. 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 begin around the 6th week of pregnancy (counting gestational age from 14 days before conception).