Nausea and vomiting are common during pregnancy; they are thought to occur because estrogen levels increase rapidly. Although vomiting in the morning (morning sickness) is typical, nausea or vomiting can occur at any time. These symptoms are most common and most severe during the 1st trimester of pregnancy. Hyperemesis gravidarum is persistent pregnancy-induced vomiting that causes significant dehydration, often with electrolyte abnormalities or ketosis. Occasionally, prenatal vitamin preparations with iron cause nausea. Rarely, severe, persistent vomiting may result from hydatidiform mole. Vomiting can also result from many nonobstetric disorders.
Vomiting is less likely to be due to pregnancy if it begins after the 1st trimester of pregnancy. Vomiting is likely to be due to pregnancy if it lasts several days to weeks, abdominal pain is absent, and other apparent causes for vomiting are absent. If hyperemesis gravidarum is suspected, urine ketones are measured; if symptoms are particularly severe or persistent, serum electrolytes are measured. A normal intrauterine pregnancy should be confirmed to rule out hydatidiform mole. Other tests are done based on clinically suspected nonobstetric disorders.
Pregnancy-induced vomiting may be relieved by drinking or eating frequently (5 or 6 small meals/day), but only small amounts of bland foods (eg, crackers, soft drinks, BRAT diet [bananas, rice, applesauce, dry toast]) should be eaten. Eating before rising may help. If dehydration (eg, due to hyperemesis gravidarum) is suspected, normal saline or Ringer's lactate is given IV, and identified electrolyte abnormalities are corrected.
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