Data on the risk of cardiac malformations following first trimester use of bupropion have been conflicting. A few studies found a small increase in the risks of ventral septal defect and left ventricular outflow tract obstruction, but the results may have been confounded by the limited number of cases and use of the drug in women who were taking it for smoking cessation (smoking is associated with an increased risk of cardiac malformations). Other data sources (studies, patient registry, patient database) have suggested that the rate of cardiovascular malformations with first trimester bupropion exposure is generally similar to the background rate in clinically recognized pregnancies. Untreated depression is associated with risks to the mother and adverse birth outcomes.

An authoritative source on drug safety in pregnancy summarized the evidence as follows: "Small increases in heart defects have been reported, but confounding by indication (e.g., use for smoking cessation) cannot be excluded. In addition, an association between bupropion and attention deficit/hyperactivity disorder (ADHD) in offspring is a concern, but cigarette smoking was a potential confounder. Additional research is required to clarify these risks. If a pregnant woman requires bupropion, she should be informed of the potential risks, but the drug should probably not be withheld. However, avoiding use in the 1st trimester should be considered."2