Objective Studies restricted to live births may underestimate severe teratogenic effects. We address the limitation by including data from both prenatal and postnatal diagnoses of cardiac malformations.

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Objective: Attention-deficit/hyperactivity disorder (ADHD) medications are increasingly used in pregnancy. Studies on the pregnancy safety of these medications that are restricted to live births may underestimate severe teratogenic effects that cause fetal demise or termination of pregnancy. The present study addresses this limitation by including data from both prenatal and postnatal diagnoses of major malformations. Methods: A nationwide registry-based study was conducted of 364,012 singleton pregnancies in Denmark from November 1, 2007, to February 1, 2014. Exposures to ADHD medication were obtained from redeemed prescriptions from the Danish Health Services Prescription Database. Outcome data included prenatally diagnosed malformations from the Danish Fetal Medicine Database and postnatally diagnosed malformations from the Danish National Patient Registry. The primary outcome was major malformations overall, and secondary outcomes were malformations of the central nervous system and cardiac malformations. The comparison group was pregnancies with no redeemed prescriptions for ADHD medication. We defined severe cardiac malformations (SCM) as concurrent diagnoses of a cardiac malformation with miscarriage, termination, stillbirth, postnatal death, or cardiac surgery within 1 year of birth. Results: The prevalence of first-trimester exposure to ADHD medication increased during the study period from 0.05% in 2008 to 0.27% in 2013, with the majority (473/569) of the exposures being to methylphenidate. There were 5.1% malformations overall and 2.1% cardiac malformations among the exposed compared to 4.6% and 1.0%, respectively, among the unexposed. For methylphenidate, the adjusted prevalence ratios (PRs) were 1.04 (95% confidence interval [CI], 0.70-1.55) for malformations overall and 1.65 (95% CI, 0.89-3.05) for any cardiac malformations (number needed to harm [NNH] = 92), with septum defects in 10 out of 12 cases. The PR for ventricular septal defect was 2.74 (95% CI, 1.03-7.28) and for SCM, 2.59 (95% CI, 0.98-6.90). Conclusions: Exposure to methylphenidate was not associated with an increased risk of malformations overall in data that included information from both prenatal and postnatal diagnoses of major malformations. There was an increased risk of cardiac malformations with NNH of 92 based on 12 cases among the exposed. More data are needed on other types of ADHD medication.

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