Nausea and Vomiting of Pregnancy - American Family Physician

Etiology and Pathophysiology The etiology of nausea and vomiting of pregnancy remains unknown, but a number of possible causes have been investigated. Although many physicians were taught that psychologic factors are responsible for nausea and vomiting of pregnancy and hyperemesis gravidarum, few data support this theory. In one well-known study, the Cornell Medical Index was administered to 44 pregnant women with hyperemesis and 49 pregnant women without hyperemesis; the Minnesota Multiphasic Personality Inventory (MMPI) was administered only to the pregnant women with hyperemesis. The MMPI data suggested that women with hyperemesis have hysteria, excessive dependence on their mothers, and infantile personalities. However, the study findings were not conclusive because comparative testing was not performed. N ausea and vomiting of pregnancy begins between the fourth and seventh week after the last menstrual period in 80 percent of pregnant women and resolves by the 20th week of gestation in all but 10 percent of these women. The condition has been shown to be more common in urban women than in rural women. One study identified increased risk in housewives and decreased risk in “white collar” or professional white women who consumed alcohol before conception, and in women over 35 years of age with a history of infertility. Hyperemesis gravidarum, a severe form of nausea and vomiting, affects one in 200 pregnant women. Although the definition of this condition has not been standardized, accepted clinical features include persistent vomiting, dehydration, ketosis, electrolyte disturbances, 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. (Am Fam Physician 2003;68:121-8. Copyright© 2003 American Academy of Family Physicians.)