Published experience on first trimester exposure to methyldopa is still limited, although it is recommended as first-line treatment for hypertensive disorders in pregnancy in most countries. The primary aim of this prospective observational cohort study was to analyze the rate of major birth defects and spontaneous abortions in women with methyldopa therapy for chronic hypertension. Outcomes of 261 pregnancies with first trimester exposure to methyldopa and 526 comparison pregnancies without chronic hypertension reported to the German Embryotox pharmacovigilance institute were evaluated. The rate of major birth defects in the exposed cohort was not significantly increased compared with the comparison cohort (3.7% versus 2.5%; adjusted odds ratio, 1.24; 95% confidence interval, 0.4–4.0). There was a tendency toward a higher rate of spontaneous abortions in exposed women. The risk of preterm birth was significantly higher, and adjusted birth weight scores were significantly lower in the methyldopa group. Head circumferences were significantly reduced in exposed boys only. There was neither evidence for an increased risk for birth defects or increase in early pregnancy loss nor evidence for growth restriction or a reduced head circumference in a sensitivity analysis comparing monotherapies with methyldopa to metoprolol. However, the significantly increased risk of preterm birth in methyldopa-treated pregnancies was confirmed. In conclusion, our study does not indicate a teratogenic risk of methyldopa. Further studies are needed to confirm its safety in the first trimester and clarify the influence of hypertension and methyldopa on preterm birth and intrauterine growth. Clinical Trial Registration— URL: https://drks-neu.uniklinik-freiburg.de/drks_web/ . Unique identifier: DRKS00010502.

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