Ondansetron use during pregnancy is somewhat controversial and requires careful consideration. Generally, it is used to treat severe nausea and vomiting during pregnancy (including hyperemesis gravidarum) and is considered effective for many patients. However, safety data are mixed:

• Some studies and expert opinions suggest ondansetron is likely safe during pregnancy with no significant increase in risks such as miscarriage, stillbirth, or major congenital malformations compared to other antiemetics. It is categorized as pregnancy category B by the FDA, indicating no conclusive evidence of harm in humans but without large definitive safety studies.

• Other data and reviews caution that ondansetron cannot be assumed fully safe; certain studies have suggested a small possible increased risk of oral clefts (cleft palate, cleft lip) and heart defects when taken in early pregnancy, particularly within the first trimester (first 12 weeks), though these risks appear to be very low.

• The decision to use ondansetron in pregnancy typically balances the severity of nausea/vomiting and the risks of dehydration or malnutrition against these potential fetal risks. It requires medical supervision, especially regarding dosage and monitoring for side effects such as rare heart rhythm problems.

In summary, ondansetron may be prescribed during pregnancy in cases of severe nausea and vomiting when other treatments fail, but it is important to discuss with a healthcare provider to weigh benefits and risks carefully, especially during the first trimester.

If you are pregnant or planning to become pregnant and considering ondansetron, consult your doctor for personalized medical advice.