ACOG Guidelines for Treating Nausea and Vomiting in Pregnant Women Reviewed

Laurie Barclay, MD

October 14, 2010

October 14, 2010 — Various strategies for treating nausea and vomiting in pregnant women are described in a review reported in the October 14 issue of the New England Journal of Medicine. The recommendations in this review are concordant with guidelines published by the American College of Obstetricians and Gynecologists and by the Society of Obstetricians and Gynaecologists of Canada for the management of nausea and vomiting in pregnancy.

"About 50% of women have nausea and vomiting in early pregnancy, and an additional 25% have nausea alone," writes Jennifer R. Niebyl, MD, from the University of Iowa Hospitals and Clinics in Iowa City.

"In about 35% of women who have this condition, nausea and vomiting are clinically significant, resulting in lost work time and negatively affecting family relationships. In a small minority of patients, the symptoms lead to dehydration and weight loss requiring hospitalization. The reported incidence of hyperemesis gravidarum is 0.3 to 1.0%; this condition is characterized by persistent vomiting, weight loss of more than 5%, ketonuria, electrolyte abnormalities (hypokalemia), and dehydration (high urine specific gravity)."

Nausea and vomiting in early pregnancy typically have no well-defined cause, but migraine headaches or gastrointestinal disorders should be considered in the differential diagnosis. Laboratory evaluation should include blood levels of blood urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, electrolytes, and amylase.

Dietary counseling to eat small amounts of food several times a day may be helpful, as well as to avoid exposure to odors, foods, or supplements that appear to trigger nausea, particularly fatty or spicy foods and iron tablets. Other helpful strategies may include eating and drinking fluids between meals or eating bland, dry, and high-protein foods. However, randomized controlled trials have not compared different types of diets to control nausea and vomiting in pregnancy.

In some women, alternative therapy remedies such as ginger and acupuncture may be effective, and these may be given at any point during the pregnancy.

For nausea and vomiting accompanying weight loss in the first trimester of pregnancy, pharmacologic therapy is indicated. Approximately 10% of women with nausea and vomiting in pregnancy require medication.

Evidence from randomized trials supports the use of vitamin B6 (pyridoxine), 10 to 25 mg every 8 hours, and doxylamine, 25 mg at bedtime and 12.5 mg each in the morning and afternoon. Unisom SleepTabs (Sanofi Aventis; oral vitamin B6 and doxylamine), which are available over the counter in the United States, have been studied in more than 6000 patients and control participants, with no evidence of teratogenicity. In randomized trials, this combination has been associated with a 70% reduction in nausea and vomiting, and the American College of Obstetricians and Gynecologists therefore recommends it as first-line therapy for nausea and vomiting in pregnancy.

For women refractory to this combination therapy, a phenothiazine, metoclopramide, or ondansetron can each be tried successively. Prochlorperazine (Compazine; GlaxoSmithKline) in a buccal tablet formulation (Bukatel; Panacea) usually causes less drowsiness and sedation than oral tablets.

The prokinetic agent metoclopramide (Reglan; tablets, Alaven; injection, Baxter) is a dopamine antagonist that rarely has been linked to tardive dyskinesia. The US Food and Drug Administration has issued a black-box warning concerning the use of Reglan in general. Because the risk for tardive dyskinesia increases with the duration of treatment and the total cumulative dose, treatment duration should not exceed 12 weeks.

Methylprednisolone should only be given after 10 weeks of gestation, and only to women who do not have symptom relief with other treatments. A meta-analysis of 4 studies showed that use of glucocorticoids before 10 weeks of gestation was associated with a 3- to 4- fold higher risk for cleft lip with or without cleft palate.

When pregnant women become dehydrated and develop high concentrations of ketones because of nausea and vomiting, intravenous fluid replacement with multivitamins, especially thiamine, is indicated. These women should be prescribed antiemetic agents, intravenously if needed, and should undergo follow-up measurement of levels of urinary ketones and electrolytes. Hospitalization may be necessary for women who continue vomiting after 12 hours of receiving intravenous fluids.

Patients who continue to lose weight despite pharmacotherapy may need enteral or parenteral nutrition.

"Patients with nausea and vomiting that are not controlled with outpatient regimens require intravenous hydration and nutritional supplementation," Dr. Niebyl writes.

"Enteral tube feeding may be effective, although some patients continue to have persistent emesis. Total parenteral nutrition is associated with a substantial risk of line sepsis (25%); steatohepatitis may also occur with the use of lipid emulsion during pregnancy. Given these risks, total parenteral nutrition should be reserved for patients with clinically significant weight loss (>5% of body weight) who have had no response to antiemetic regimens and whose condition cannot be managed with enteral feedings."

Dr. Niebyl has disclosed no relevant financial relationships.

N Engl J Med. 2010;363:1544-1550.

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