Pivmecillinam and adverse birth and neonatal outcomes: a population-based cohort study

A previous study unexpectedly showed an increased, statistically imprecise, risk of low Apgar score in children of women redeeming prescriptions for pivmecillinam in late pregnancy. To improve statistical precision we extended the previous dataset with data for 5 more y, and in addition added more neonatal outcomes. We thus examined the risk of adverse birth and neonatal outcomes among pregnant users of pivmecillinam based on population-based registries in North Jutland County, Denmark. We included 63,659 women with a live birth, or stillbirth after the 28th week of gestation. 2031 had redeemed prescriptions for pivmecillinam any time during pregnancy, 559 in the first trimester and 371 within 28 d before delivery. Adjusted odds ratios were: birth defects 0.83 (95% confidence interval (95% CI) 0.53-1.32) for exposure during first trimester, preterm delivery 0.96 (95% CI 0.79-1.18) and low birth weight 0.79 (95% CI 0.52-1.20) for exposure any time during pregnancy, and stillbirth 1.19 (95% CI 0.30-4.80), low Apgar score 1.17 (95% CI 0.37-3.66), hypoglycaemia 1.03 (95% CI 0.53-2.00), and respiratory distress syndrome 0.79 (95% CI 0.38-1.68) for exposure within 28 d before delivery. Use of pivmecillinam during pregnancy did not appear to increase the risk of adverse birth and neonatal outcomes; however, statistical precision is still low.