The anti-nausea and vomiting medication Zofran is not approved to treat morning sickness in pregnant women, but it is the most commonly prescribed treatment for women suffering from morning sickness. Despite its frequent off-label use, there is limited and conflicting data on the effects of Zofran on developing fetuses.
Zofran, known chemically as ondansetron, is approved for the prevention of chemotherapy- and radiation-induced nausea and vomiting, as well as postoperative nausea and vomiting. The drug works by blocking serotonin in the areas of the brain that trigger nausea and vomiting.
In 2004, a cohort study comparing rates of miscarriage, stillbirth and major birth defects in women treated with Zofran as well as other anti-nausea drugs found no significant difference in the pregnancy outcomes. However, the study was sponsored by the drug industry.
A larger case-control study linked Zofran to a significantly increased risk for cleft palate compared to women who did not take anti-nausea drugs while pregnant. Additionally, an Australian study found a 20 percent increased risk for a major birth defect in infants exposed to Zofran during the first trimester of pregnancy. Other studies have linked Zofran use to a greater risk of heart septum defects.
The Food and Drug Administration (FDA) does not approve of Zofran as a treatment for morning sickness. But, doctors have the authority to prescribe drugs for conditions for which they are not approved. Drug companies, however, cannot promote their products for off-label uses.
Yet, GlaxoSmithKline, maker of Zofran, from 2002 to 2004 heavily promoted the drug to doctors as a morning sickness treatment. Since then, the FDA has received more than 500 reports of birth defects in babies born to women who were treated with Zofran while pregnant.