Impact of β-Blockers on the Risk of Low-Birth-Weight Infants in Women with Long QT Syndrome or Marfan Syndrome: A Single-Center Retrospective Study from 2008 to 2022 in a Tertiary Care Center.

To our knowledge, this is the first study specifically focusing on β-blocker use in pregnant women with LQTS or MFS and structurally normal hearts, using matched controls to minimize confounding by underlying cardiac disease. β-Blocker use-mainly nadolol and bisoprolol-was associated with significantly lower birth weight and higher rates of FGR/SGA and neonatal bradycardia. Our findings support the continuation of β-blocker therapy when clinically indicated, combined with careful fetal growth monitoring and targeted neonatal surveillance.