OBJECTIVES: To compare pregnancy loss rates, preterm birth rates and gestational age at delivery in women vaccinated against COVID-19 during pregnancy vs. those unvaccinated.

METHODS: Data were captured from Dorsata Prenatal, an electronic medical record (EMR) system that captures obstetrical data for tens of thousands of pregnancies annually. Patients who delivered between February 11, 2021-June 2, 2022, were included. The vaccinated group included women who had at least one COVID-19 vaccination documented in their EMR between 30 days prior to pregnancy and delivery. The unvaccinated group included women without a COVID-19 vaccination documented. The primary outcome measure was gestational age (GA) at delivery. We analyzed the data using chi-square tests, with significance set at p<0.01.

RESULTS: A total of 51,994 pregnant women were identified—7,947 (15.3%) in the vaccinated group and 44,047 (84.7%) in the unvaccinated group. Vaccination rate varied by race (Asian: 19.7%; White: 17.3%; Black: 11.2%, P<0.001), ethnicity (Latino: 8.6%; Not-Latino: 18.7%; P<0.001), marital status (Married: 19.2%; Single: 8.8%; P<0.001), mother’s age (≥35 years: 20.0%; <35 years 14.2%; P<0.001), and region (Northeast: 19.2%; South: 15.2%; West: 9.1%; P<0.001). The vaccinated group had significantly lower rate of preterm delivery (Gestational Age [GA]<37 weeks; vaccinated: 7.8% vs. unvaccinated: 9.6%; P<0.001), and significantly lower rates of pregnancy loss (GA<20 weeks; vaccinated: 1.1% vs. unvaccinated: 4.1%; P<0.001).

CONCLUSIONS: This is one of the largest real-world studies to date in women who received the COVID-19 vaccination during pregnancy. Vaccination rates varied significantly across race/ethnicity. Vaccinated patients had lower preterm delivery and pregnancy loss rates compared with unvaccinated patients.