Pregnant people who contract COVID-19 have an increased risk of disease severity and death, yet only 31% of pregnant people in the United States had received vaccines as of September 2021. One barrier to vaccine acceptance is the concern that vaccination might disrupt pregnancy.

A Yale co-led study, which looked at more than 40,000 pregnant individuals, adds new evidence supporting the safety of COVID-19 vaccination during pregnancy.

The study found COVID-19 vaccination during pregnancy was not associated with preterm birth or small-for-gestational-age (SGA) when comparing vaccinated with unvaccinated pregnant people. The trimester when the vaccination was received and the number of COVID-19 vaccine doses received were also not associated with increased risk of preterm birth or SGA, the researchers found.

The findings were reported Jan. 4 by the Centers for Disease Control and Prevention (CDC).