New large safety study on anti-nausea medication use in pregnancy is reassuring

Ondansetron is a drug used for nausea and vomiting, and its use in pregnancy has increased during the last few years. In a paper published in the New England Journal of Medicine, researchers from Statens Serum Institut report that there was no evidence that ondansetron use in pregnancy was detrimental to the fetus.

First study of the safety of ondansetron use in pregnancy

“We know that ondansetron (marketed in Denmark under the trade names Ondansetron and Zofran) is prescribed to pregnant women who experience nausea and vomiting in pregnancy (“morning sickness”), at least those with severe symptoms. We also know that the use of this drug in pregnancy has increased in recent years. However, no one has looked into whether ondansetron is safe to use in pregnancy. That is, prior to our study, it was unknown whether this medication damages the fetus.” says lead researcher Björn Pasternak, MD, PhD.

Gravid mave

No need to fear adverse effects of anti-nausea medication in pregnancy

Registry-based study

The researchers identified all pregnant women in Denmark between the years 2004 and 2011 using nationwide registries. Women using ondansetron were matched with women who did not use this drug but were otherwise similar with respect to age, pregnancy history, medical conditions, and other characteristics. In total, 1970 pregnant women who used ondansetron at some time during pregnancy were identified. Of these, 1233 used this drug in the first trimester of pregnancy, which is the time period when the fetus is most sensitive to insults that may lead to congenital malformations.

No evidence of increased risk of adverse effects

In the statistical analyses, the researchers found no evidence of adverse effects from ondansetron. There was no increased risk of any of the outcomes that were studied, including major birth defects, preterm delivery, spontaneous abortion, stillbirth, and no indication of increased risk of fetal growth restriction.
“Although these results cannot definitively rule out the possibility of adverse effects in association with ondansetron, the results do provide reassurance regarding the use of this agent for nausea and vomiting in pregnancy.” the researchers write in the conclusion of the paper, which is published in the February 28 issue of the New England Journal of Medicine.

Read the scientific article

Pasternak B, Svanström H, Hviid A. Ondansetron in Pregnancy and Risk of Adverse Fetal Outcomes. N Engl J Med 2013;368:814-823

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Department of Epidemiology Research
Björn Pasternak

Tel: +45 3268 8150