For more than 2 decades, respiratory syncytial virus (RSV) has been the leading cause of infant hospitalizations in the US, with the greatest burden occurring in the first months of life. Starting in 2023, a long-acting monoclonal antibody for infants (nirsevimab) and the maternally administered bivalent prefusion F subunit-based RSV vaccine (RSVpreF) were recommended in the US to prevent severe RSV infections among infants. RSVpreF is recommended between 32 and 36 weeks of pregnancy, with seasonal administration from September through January. The narrow window for use was informed by clinical trial data that found a slightly higher rate of preterm birth in RSVpreF recipients compared with placebo. However, this narrow window for vaccination relatively late in pregnancy may introduce unique biases to observational studies; these biases are incompletely understood. Although clinical studies of maternal RSVpreF are limited, there is a growing evidence base for the safety of this product. Thus far, no postlicensure studies have identified an association between maternal RSVpreF and preterm birth, to our knowledge.