November 3, 2021 4:16 PM EDT

The American College of Obstetricians and Gynecologists (ACOG) now recommends that all pregnant and recently pregnant individuals receive a COVID-19 booster shot when they are eligible, according to guidance published on Nov. 3. That means someone who is pregnant should get a booster at least two months after receiving the single-dose Johnson & Johnson/Janssen vaccine, or at least six months after the second dose of an mRNA vaccine made by either Pfizer-BioNTech or Moderna.

“Because pregnancy puts you at increased risk for severe disease and at risk for poor pregnancy outcomes like preterm birth, ACOG does feel it’s important to recommend a booster for pregnant persons who are eligible,” says Dr. Denise Jamieson, an OB/GYN at Emory University School of Medicine and a member of ACOG’s Immunization, Infectious Disease, and Public Health Preparedness work group.

Federal health officials have authorized boosters for anyone who got the Johnson & Johnson shot, as well as certain groups of people who got the Pfizer-BioNTech or Moderna shots. Those groups include elderly adults, people who live or work in high-exposure settings and those who have underlying medical conditions.

“Pregnancy is not a pathologic condition,” says Dr. Emily Adhikari, a maternal-fetal medicine physician at UT Southwestern Medical Center. But given the risks COVID-19 poses both to pregnant people and their babies, the U.S. Centers for Disease Control and Prevention (CDC) includes pregnancy on its list of underlying medical conditions that make someone eligible for a booster dose.

Vaccination rates among pregnant people have been low throughout the pandemic, in part because the shots were not studied among pregnant individuals before they were authorized, initially leaving experts somewhat cautious to whole-heartedly recommend them. The CDC strengthened its guidance in August, urging all pregnant individuals to get vaccinated and emphasizing that researchers have not found safety concerns related to COVID-19 vaccination for parent or baby. Nonetheless, as of Oct. 30, less than 40% of pregnant people in the U.S. said they’d been fully vaccinated prior to or during pregnancy.

Adhikari says encouraging pregnant individuals to get their first-round COVID-19 shots remains top priority. But for those who were vaccinated long enough ago to be eligible for a booster, it makes sense to get one, she says.

Dr. Erica Hardy, an infectious disease physician at Rhode Island’s Women & Infants Hospital, adds that booster shots appear just as safe as the original shots, according to the research that exists so far. “Doing something feels more risky, whereas not doing something doesn’t feel as immediately risky,” she says. “But the risk of COVID is quite severe.”

Like the general public, pregnant individuals can receive any booster shot, regardless of which vaccine they initially received, according to ACOG’s guidance. There are not yet strong data to say which combination is best, but Jamieson notes that a very small number of women have experienced serious blood clotting after getting the Johnson & Johnson shot. “It is something that pregnant persons may want to think about,” she says.

A booster’s primary purpose is to prevent severe disease and keep both parent and baby out of the hospital—but an extra vaccine dose may pass additional antibodies along to the newborn, too. Based on studies from the first round of COVID-19 vaccination, experts know that “vaccination in the third trimester seems to be really good at boosting … antibodies both in the mother and in cord blood, and then in breast milk,” Adhikari says. It’s reasonable to assume the same would be true of boosters, though there aren’t yet many studies to prove it.

Jamieson says pregnant individuals shouldn’t worry too much about timing their booster to maximize the number of antibodies they pass on. Instead, she says it’s smart to get a booster as soon as possible, to minimize the damage of a potential COVID-19 exposure.

While getting boosted later in pregnancy may offer “subtle differences in antibody transfer to the fetus,” Jamieson says, “they’re not outweighed by the overall risks of being sick with COVID when you’re pregnant.”

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Write to Jamie Ducharme at jamie.ducharme@time.com.

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