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Am Fam Physician. 2004;70(3):601

Nausea and Vomiting in Pregnancy

The American College of Obstetricians and Gynecologists (ACOG) has released a new guideline on diagnosing and treating nausea and vomiting (morning sickness) in pregnancy. “ACOG Practice Bulletin No. 52: Nausea and Vomiting of Pregnancy,” appears in the April 2004 issue of Obstetrics and Gynecology and is available online at

The guideline reviews the prevalence, risk factors, and clinical recommendations in treating morning sickness. While the cause of morning sickness remains unknown, there are effective treatments to prevent and treat the problem.

Nausea and vomiting are common in early pregnancy, affecting 70 to 85 percent of pregnant women. Morning sickness typically begins within the first nine weeks of pregnancy, with symptoms ranging from mild to severe. Severe morning sickness (hyperemesis gravidarum) occurs in approximately 0.5 to 2 percent of pregnancies. It is the most common indication for hospitalization during early pregnancy and second only to preterm labor as the most common reason for hospitalization during pregnancy.

According to ACOG, some pregnant women have a higher risk of having hyperemesis gravidarum. They include women carrying multiple fetuses, daughters and sisters of women who had the condition, women carrying a female fetus, and women with a history of hyperemesis gravidarum in a previous pregnancy. Other risk factors include a history of motion sickness or migraines.

Some women do not seek treatment for morning sickness because of concerns about treatment safety. Yet, once symptoms progress, treatment can become more difficult. Mild cases may be resolved with lifestyle and dietary changes, and safe and effective treatments are available for more severe cases.

The following recommendations for the prevention and treatment of nausea and vomiting of pregnancy are based on consistent scientific evidence:

  • Taking a multivitamin at the time of conception may decrease the severity of symptoms.

  • Taking Vitamin B6 alone or with doxylamine (an antihistamine) is safe and effective and should be considered a first-line treatment.

The following recommendations are based on limited or inconsistent scientific evidence:

  • Ginger has shown beneficial effects and can be considered a nonpharmacologic option.

  • Antihistamine H1-receptor blockers, phenothiazines, and benzamines have been shown to be safe and effective in treating refractory cases.

  • Early treatment of symptoms is recommended to prevent progression to hyperemesis gravidarum.

  • Treatment with methylprednisolone (a steroid) may be effective in severe cases, but should be a treatment of last resort because of its potential risk to the fetus.

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