COVID-19 Vaccination Lowers Risks for Pregnant People and Babies

Credit: Adobe Stock/Anna

Results from a new study published in JAMA showed COVID-19 vaccination before or during pregnancy reduces the risk of severe illness, critical care unit admission and preterm birth for pregnant individuals who get infected.

“There is never a bad time to be vaccinated — whether you’re currently pregnant or planning a pregnancy,” said lead investigator Elisabeth McClymont, Ph.D., assistant professor in the University of British Columbia’s Department of Obstetrics and Gynaecology. “But our data suggest there may be added benefits to receiving the vaccine during pregnancy.”

Previous research, which used data from the Canadian Surveillance of COVID-19 in Pregnancy (CANCOVID-Preg) program, linked infection during pregnancy to an increased risk of adverse maternal outcomes. These risks were amplified among women with preexisting conditions (e.g., hypertension, diabetes, asthma), those who had a greater body mass index and those who were older.

Other studies have shown vaccination has a protective effect against negative maternal and infant outcomes following a COVID-19 infection. However, these studies included smaller sample sizes, necessitating further research involving larger, prospective cohorts of patients.

The current study examined whether COVID-19 vaccination helps protect pregnant individuals who get infected with SARS-CoV-2 from severe illness and complications for both the parent and the baby by analyzing 19,899 cases in Canada. Most participants were aged 30 to 35 years and over half identified as White. About 72% of the participants were vaccinated before their COVID-19 diagnosis, with the majority receiving the vaccine prior to pregnancy and a smaller portion during pregnancy, while 28% were unvaccinated.

The study included infections that occurred during both the delta and omicron variant periods, and all cases were followed until the end of pregnancy to assess outcomes for both the pregnant person and their infant.

Results demonstrated that vaccination was associated with a lower risk of severe COVID-19 outcomes. Vaccinated individuals had a 62% lower risk of hospitalization compared with unvaccinated individuals during both the delta and omicron periods. The risk of admission to a critical care unit was reduced by 90% among those vaccinated.

Vaccination was also linked to a lower risk of preterm birth, with a 20% lower risk during the delta period and a 36% lower risk during omicron. These benefits remained significant even after accounting for other health conditions, with unvaccinated individuals facing nearly four times higher risk of hospitalization during delta and more than twice the risk during omicron.

“Our findings provide clear, population-level evidence that COVID-19 vaccination protects pregnant people and their babies from serious complications,” said senior investigator Deborah Money, M.D., a professor of obstetrics and gynecology at the University of British Columbia. “Even as the virus evolved, vaccination continued to offer substantial benefits for both mother and child.”

However, investigators mentioned some study limitations to keep in mind. Some mild COVID-19 cases during the omicron period were likely missed because people tested at home and did not seek medical care, meaning the reported hospitalization rates are likely higher than the true rates. In addition, the study could not prove cause and effect, did not include booster dose data and relied on population-level estimates of variants, so results may differ with newer variants circulating today.

Overall, these results highlight that vaccination can help safeguard both the health of the pregnant person and the baby, regardless of the variant of the virus.

“Pregnancy is a unique period of vulnerability but also of opportunity for prevention,” said McClymont. “This study reinforces how vaccination can make a real difference for maternal and newborn health.”