Mar. 29, 2021 -- The Pfizer-BioNTech and Moderna coronavirus vaccines are safe and effective in pregnant and breastfeeding women, according to a new study published Thursday in the American Journal of Obstetrics & Gynecology.

The study also found that mothers can pass antibodies to their newborns.

“That’s a very important piece of information to our patients,” Andrea Edlow, MD, the senior study author and a maternal-fetal medicine specialist at Massachusetts General Hospital, told ABC News.

“We know that this vaccine works for you,” she added.

The research team studied a group of 131 women who received the Pfizer or Moderna vaccine, including 84 pregnant, 31 breastfeeding and 16 non-pregnant women. All three groups had similar high antibody levels. The study also found no significant differences in vaccine side effects between pregnant and non-pregnant women.

Compared to pregnant women who had recovered from COVID-19, pregnant women who received the vaccine had “strikingly higher” antibody levels, the authors wrote. In addition, women who received the Moderna vaccine had higher antibody levels than those who received the Pfizer vaccine.

The research team also found that vaccine-generated antibodies were present in all of the umbilical cord and breast milk samples that were tested, which suggests that pregnant women and breastfeeding women can pass COVID-19 antibodies to their fetuses and newborns.

“That is the most comforting piece of information that’s out there,” Galit Alter, MD, one of the study authors and a professor of medicine at the Ragon Institute in Massachusetts, told ABC News.

The research team found neutralizing antibodies in the blood of pregnant women, which indicates that the antibodies can kill the coronavirus. However, the neutralizing antibodies were lower in umbilical cord samples, so more research is needed to understand whether babies have a high enough immunity when born with antibodies, the study authors said.

Future studies could also determine when women should get vaccinated during pregnancy for maximum protection, the authors wrote. Additional studies will be needed for the Johnson & Johnson and AstraZeneca vaccines as well.

“On a daily basis, we’re taking care of patients who want to know if the vaccine is effective in pregnancy and what the risks are,” Edlow said. “Having real scientific data to counsel people on goes a long way toward relieving vaccine hesitancy.”

Show Sources

American Journal of Obstetrics & Gynecology, “COVID-19 vaccine response in pregnant and lactating women: a cohort study.”
ABC News, “Pfizer and Moderna are safe and effective in pregnant women, provide antibodies to newborns.”

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