Clinical Context

At some point during pregnancy, 50% to 80% of women have nausea and 50% have vomiting. Approximately half of pregnant women have nausea and vomiting, one-quarter have nausea only, and one-quarter are unaffected. Nausea and vomiting of pregnancy affects the health of the pregnant woman and her baby, and it can reduce quality of life and significantly contribute to healthcare costs and time lost from work.

Because "morning sickness" is common in early pregnancy, it may be undertreated, particularly as some women do not seek treatment because of concerns about medication safety. Therefore, the American College of Obstetricians and Gynecologists (ACOG) has issued an updated Practice Bulletin to review the best available evidence about the diagnosis and management of nausea and vomiting of pregnancy.

Guideline Synopsis and Perspective

Guidelines published online August 19 by ACOG and in the September issue of Obstetrics & Gynecology review the evidence on diagnosing and managing nausea and vomiting during pregnancy.

Among the new guidelines, replacing those from 2004, are updates on widely known treatments. The combination of doxylamine and vitamin B₆, which was taken off the market in 1983, is back and has been proven safe and effective. ACOG says the combination should be considered first-line pharmacotherapy.

For ondansetron, the review includes a list of medications that patients taking the drug should avoid. Although some studies have shown an increased risk for birth defects with early ondansetron use, other studies have not, and the absolute risk to any fetus is low, according to the review. As with all medications, the risks and benefits should be weighed in each case.

Symptoms Underreported and Undertreated

An estimated 50% of pregnant women experience nausea and vomiting, 25% have nausea only, and 25% are unaffected, the authors report. Recurrence with subsequent pregnancies ranges from 15.2% to 81%.

However, nausea and vomiting may not receive the attention they need for several reasons. One is that "morning sickness" is common in early pregnancy, so pregnant women and their clinicians may minimize the concern, and it may be undertreated. Also, women may not seek help because of concerns about the safety of medications.

However, the guideline authors note that treating nausea and vomiting early in pregnancy, before it progresses, can help control symptoms and prevent more serious complications, including hospitalization.

Considering the timing of the start of nausea or vomiting is important. Symptoms almost always present before 9 weeks of gestation. When nausea or vomiting begins for the first time after 9 weeks, other conditions should be considered.

Other recommendations based on good and consistent scientific (level A) evidence include:

• The standard recommendation to take prenatal vitamins for 3 months before conception may reduce the incidence and severity of nausea and vomiting in pregnancy.
• In patients with hyperemesis gravidarum who also have suppressed thyroid-stimulating hormone levels, treatment of hyperthyroidism should not begin without evidence (such as goiter, thyroid autoantibodies, or both) of thyroid disease.

Among recommendations based on limited or inconsistent scientific evidence (level B):

• Treatment with ginger has shown benefit in reducing nausea and can be considered a nonpharmacologic option.
• Treatment of severe nausea and vomiting of pregnancy or hyperemesis gravidarum with methylprednisolone may be effective in refractory cases; however, the risk profile of methylprednisolone suggests that it should be used as a last resort.

The authors acknowledge that variations in treatment may be warranted based on the needs of the individual patient, resources, and limitations unique to the practice.

Whether, when, and how to treat nausea and vomiting of pregnancy should also depend on the woman's perception of the severity of her symptoms. Easing the symptoms can add to women's quality of life, lower healthcare costs, and shortened time away from work.

Obstet Gynecol. 2015;126:687-688. Abstract

Guideline Highlights

• Treatment in the early stages of nausea and vomiting of pregnancy may help prevent hospitalization and other serious complications, because it can become more difficult to control symptoms if left untreated.
• Lifestyle and dietary changes may resolve mild cases of nausea and vomiting of pregnancy, and safe and effective treatments are available for more severe cases.
• The woman's perception of symptom severity greatly affects the decision of whether, when, and how to treat nausea and vomiting of pregnancy.
• Clinicians should distinguish nausea and vomiting of pregnancy from nausea and vomiting from other causes.
• Nausea and vomiting of pregnancy nearly always begins before 9 weeks of gestation; symptoms presenting later in pregnancy should prompt the clinician to consider other causes.
• Use of prenatal vitamins for 3 months before conception may decrease the incidence and severity of nausea and vomiting of pregnancy (level A recommendation).
• First-line pharmacotherapy for nausea and vomiting of pregnancy is vitamin B₆ or vitamin B₆ plus doxylamine, which are safe and effective (level A).
• Women with hyperemesis gravidarum and suppressed thyroid-stimulating hormone levels should not be treated for hyperthyroidism without evidence of intrinsic thyroid disease, such as goiter and/or thyroid autoantibodies (level A).
• A nonpharmacologic option to treat nausea and vomiting of pregnancy is ginger, which has been shown to reduce nausea (level B).
• To prevent progression to hyperemesis gravidarum, ACOG recommends early treatment of nausea and vomiting of pregnancy (level B).
• In refractory cases, methylprednisolone may be effective for severe nausea and vomiting of pregnancy or hyperemesis gravidarum, but it should be a last resort because of its risk profile (level B).
• Women who cannot tolerate oral liquids for a prolonged period or who have clinical signs of dehydration should receive intravenous hydration including dextrose and vitamins. Thiamine should be given before dextrose infusion to prevent Wernicke encephalopathy (level C).
• Woman with hyperemesis gravidarum who are unresponsive to medical therapy and who cannot maintain their weight should receive nutritional support by nasogastric or nasoduodenal enteral tube feeding as first-line treatment (C).
• Because of significant complications and the potential of severe maternal morbidity associated with peripherally inserted central catheters, these should not be used routinely in women with hyperemesis gravidarum, but only as a last resort.
• The performance measure in this guideline is the proportion of women experiencing nausea and vomiting of pregnancy who are treated with vitamin B₆ or vitamin B₆ plus doxylamine as first-line pharmacotherapy.

Clinical Implications

• For mild cases of nausea and vomiting of pregnancy, lifestyle and dietary changes may suffice, and safe and effective treatments are available for more severe cases, according to the updated ACOG Practice Bulletin.
• Women experiencing nausea and vomiting of pregnancy who cannot tolerate oral liquids for a prolonged period or who have clinical signs of dehydration should receive intravenous hydration including dextrose and vitamins. If they cannot maintain their weight, they should receive nutritional support by enteral tube feeding.
• Implications for the Healthcare Team: Members of the healthcare team should be aware that nausea and vomiting of pregnancy nearly always begins before 9 weeks of gestation, and that these symptoms presenting later in pregnancy may stem from another cause.

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