evidence: Results of this cohort study suggest that COVID-19 vaccination was safe during pregnancy from the perspective of infant neurodevelopment to 18 months of age. Additional longer-term research should be conducted to corroborate these findings and buttress clinical guidance with a strong evidence base. [...] Problematically, pregnant individuals were excluded from the initial large-scale randomized clinical trials of COVID-19 vaccines. Despite subsequent demonstrations of COVID-19 vaccine safety and efficacy in pregnant individuals4-7 and guidance from professional organizations recommending vaccination of this population,8 vaccine hesitancy obstructed universal vaccine uptake. As of May 2022, the majority of those planning pregnancy or currently pregnant expressed doubt if pregnant people should get the COVID-19 vaccine in a Kaiser Family Foundation study.9 Indeed, early safety data focused on vaccine adverse effects and short-term perinatal outcomes such as miscarriage and preterm birth,6 but longer-term offspring developmental outcomes could not yet be assessed when real-time guidance was issued. [...] We observed differential outcomes of exposure on neurodevelopmental delay by sex. Maternal COVID-19 vaccination was associated with increased risk of abnormal ASQ-3 screen at 12 months in male infants but not at 18 months. Interestingly, an electronic heath record study from 2 prominent Massachusetts health systems examining International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, billing codes for neurodevelopmental disorders identified an increased risk for neurodevelopmental disorders at 12 months among male but not female infants after in utero exposure to COVID-19 infection; this association was similarly not sustained at 18 months.27 It is unclear whether these findings, in conjunction with those of our study, are spurious or associated with a true but transient phenomenon linking inflammatory exposures to developmental trajectories.