Nausea and Vomiting of Pregnancy

Print

The exact cause of nausea and vomiting of pregnancy remains unclear, but it is generally mild, self-limited condition that may be controlled with conservative measures. Few data support the theory that psychological factors are responsible for nausea and vomiting of pregnancy. Delayed gastric motility caused by progesterone, may be responsible for nausea and vomiting of pregnancy, but the roles of other hormones (human chorionic gonadotropin and estrogen) which also increase during pregnancy, are controversial.

A small percentage of pregnant women have a more profound course of nausea and vomiting, with the most severe form being hyperemesis gravidarum, which affects one in 200 pregnant women. The clinical features of hyperemesis gravidarum include persistent vomiting, dehydration, ketosis, electrolyte disturbances, and weight loss (more than 5% of body weight). Multiple gestation, gestational trophoblastic disease, triploidy, trisomy 21 syndrome (Down syndrome), and hydrops fetalis have been associated with an increased incidence of hyperemesis gravidarum. A recent study suggested that chronic infection with Helicobacter pylori may play a role in hyperemesis gravidarum. Hyperemesis gravidarum, may have negative implications for maternal (e.g. esophageal rupture) and fetal health (e.g. fetal growth restriction and mortality).

Pregnant women with persistent nausea and vomiting or worsening symptoms or if nausea and vomiting begin after nine weeks of gestation, should be carefully evaluated to rule out the most common pregnancy-related (hyperemesis gravidarum, acute fatty liver of pregnancy, and preeclampsia) and nonpregnancy-related causes of vomiting (gastrointestinal disorders, genitourinary tract disorders, metabolic disorders, neurologic disorders, and drug toxicity or intolerance).

Initial treatment for women with mild nausea and vomiting of pregnancy should be conservative and should involve dietary changes and emotional support. They should be instructed to eat frequent, small meals and to avoid smells and food textures that cause nausea. Solid food should be bland tasting, high in carbohydrates, and low in fat. Salty foods (e.g. salted crackers, potato chips) usually can be tolerated early in the morning, and sour and tart liquids (e.g. lemonade) often are tolerated better than water. Pregnant women with depression or other affective changes should receive appropriate emotional support.

Women with more complicated nausea and vomiting of pregnancy may need pharmacologic treatment. Pyridoxine (vitamin B₆) has been shown to be safe and effective treatments. If Pyridoxine therapy is unsuccessful, a trial of antiemetics/ antihistamines/ anticholinergics/ motility drugs is warranted (e.g. metoclopramide, diphenhydramine, meclizine, dimenhydrinate, or ondansetron).

Pregnant women with severe vomiting may require hospitalization to have intravenously administered therapy and enteral or total parenteral nutrition.