Given JE, et al. - Using malformed controls, population based exploratory case-control study was conducted to examine whether exposure to metformin during the first trimester of pregnancy, for diabetes or other indications, increases the risk of all or specific congenital anomalies. Participants in the study were 50,167 babies affected by congenital anomaly including live births, fetal deaths from 20 weeks’ gestation, and terminations of pregnancy for fetal anomaly. Researchers did not find evidence for an increased risk of all non-genetic congenital anomalies combined following exposure to metformin during the first trimester. Outcomes suggested that a signal for an increased risk of pulmonary valve atresia could be a chance finding.