Nausea and vomiting of pregnancy.

Nausea and vomiting of pregnancy, commonly known as "morning sickness," affects approximately 80 percent of pregnant women. Although several theories have been proposed, the exact cause remains unclear. Recent research has implicated Helicobacter pylori as one possible cause. Nausea and vomiting of pregnancy is generally a mild, self-limited condition that may be controlled with conservative measures. A small percentage of pregnant women have a more profound course, with the most severe form being hyperemesis gravidarum. Unlike morning sickness, hyperemesis gravidarum may have negative implications for maternal and fetal health. Physicians should carefully evaluate patients with nonresolving or worsening symptoms to rule out the most common pregnancy-related and nonpregnancy-related causes of severe vomiting. Once pathologic causes have been ruled out, treatment is individualized. Initial treatment should be conservative and should involve dietary changes, emotional support, and perhaps alternative therapy such as ginger or acupressure. Women with more complicated nausea and vomiting of pregnancy also may need pharmacologic therapy. Several medications, including pyridoxine and doxylamine, have been shown to be safe and effective treatments. Pregnant women who have severe vomiting may require hospitalization, orally or intravenously administered corticosteroid therapy, and total parenteral nutrition.