Zofran Causing Birth Defects

Key Screening criteria:

  • Need first trimester exposure
  • Fetal heart defect

Zofran (ondansetron) is an anti-nausea drug that is FDA-approved for chemotherapy and surgery patients. It was created by GlaxoSmithKline (GSK) and has been on the market since 1991.The U.S. Food and Drug Administration approved Zofran to help cancer patients with nausea after treatments or after surgery. It helped people who vomited as a side effect from chemotherapy or who grew sick after taking post-op meds to help with pain or other complications. But drugmaker GlaxoSmithKline soon found other patients to take the drug – pregnant women suffering from morning sickness. There was just one problem. The FDA never approved Zofran for use by pregnant women.

Zofran is not approved for pregnant women. Fetal safety data is based on less than 200 births and the FDA classifies Zofran as a “Pregnancy Category B” medication, which means no one knows if it is safe. According to several studies published in the last decade, Zofran passes from mother to fetus through the placenta very rapidly and in “significant amounts.” Furthermore, it remains active in the fetus much longer than in the mother.

Zofran and Birth Defects

In February 2013, a study published in the New England Journal of Medicine looked at data from Denmark and found no association between Zofran and birth defects — but other studies dispute these results.

Other researchers have looked at the same data from Denmark, but with more pregnancies and over a longer period of time. In August 2013, they published a study (PDF) linking Zofran with a doubled risk of heart defects, leading to a 30% increased risk of birth defects overall. Of the 1,248 women who used Zofran during the first trimester, 4.7% had a baby with a birth defect, compared to 3.5% of women who did not use Zofran. Conclusions were based on nearly 900,000 pregnancies between 1997 and 2010.

Zofran and Heart Defects

In December 2014, Reproductive Toxicology published a study by researchers in Sweden who found that Zofran doubled the risk of septal heart defects (also known as “hole in the heart” defects). Conclusions were based on data from 1,349 infants whose mothers took Zofran in early pregnancy from 1998-2012.