A study by the Defense Health Agency’s Armed Forces Health Surveillance Division found that COVID-19 infection during or prior to pregnancy increased certain health risks for U.S. service members, while COVID-19 vaccination did not raise, and in some cases reduced, the likelihood of complications.
The analysis examined nearly 40,000 deliveries among active-duty service women from 2021 to 2023. Researchers compared pregnancy outcomes among 5,190 women who contracted COVID-19 during pregnancy, 6,491 who had it before pregnancy, 9,263 who were vaccinated while pregnant, and 22,056 who were vaccinated before pregnancy.
According to findings published in the October issue of the Medical Surveillance Monthly Report, infection during pregnancy was associated with higher rates of eclampsia and antepartum hemorrhage. Infection before pregnancy correlated with increased risk of hemorrhage and premature rupture of membranes.
Vaccination during pregnancy was linked to lower rates of bleeding, and vaccination prior to pregnancy was associated with reduced incidence of preterm labor and delivery. Researchers stated, “This analysis found no significant difference in adverse pregnancy outcomes among those who received a COVID-19 vaccine prior to delivery compared to women who did not.”
Earlier research in the general population has shown that COVID-19 infection is linked to increased risks of preeclampsia, stillbirth, preterm birth, and neonatal intensive care admission. Other studies have found no safety concerns related to vaccination during pregnancy, and a December study in JAMA showed that vaccinated individuals who later contracted COVID-19 were less likely to be hospitalized or deliver early.
Despite this evidence, the Centers for Disease Control and Prevention (CDC) in May removed the COVID-19 vaccine from its list of recommended immunizations for pregnant individuals. Health and Human Services Secretary Robert F. Kennedy Jr., who has questioned vaccine safety, said the change supports the administration’s health goals.
Medical organizations objected. The American College of Obstetricians and Gynecologists continues to recommend COVID-19 vaccination during pregnancy. In July, the American Academy of Pediatrics and other health groups filed a lawsuit against Kennedy, alleging the change circumvented established advisory processes.
The vaccine, developed during Trump’s first term as part of Operation Warp Speed, used messenger RNA (mRNA) technology to train the immune system. More than 2 million service members received the two-dose vaccine following a Department of Defense mandate.
Researchers noted limitations, including potential undercounting of COVID-19 infections in the dataset, incomplete vaccination, and possible miscoding of bleeding diagnoses. Despite these, they concluded the findings indicate a benefit to COVID-19 vaccination for those pregnant or planning to become pregnant, though the study did not assess booster doses.
