Two of the COVID-19 vaccines currently authorized for emergency use by the U.S. Food and Drug Administration require two doses to reach the full level of protection. But what happens if a woman finds out she’s pregnant after receiving the first dose of the vaccine? Should she get the second dose? Johns Hopkins Medicine experts say yes.

“At this time, there’s no evidence that the COVID-19 vaccine increases risks for unborn babies in the first trimester, so if a woman gets the first dose of the vaccine around the time she gets pregnant, it’s recommended that she go ahead and get the second shot,” says Jeanne Sheffield, M.D., director of maternal-fetal medicine and professor of gynecology and obstetrics at the Johns Hopkins University School of Medicine.

Research studies have shown that women who are pregnant and develop COVID-19 are at an increased risk for severe illness, complications and death compared to non-pregnant women. Moreover, many pregnant women have medical conditions that may further increase the danger.

“Women should talk with their doctor to discuss all factors about the vaccine and their pregnancy,” says Sheffield.

Getting a COVID-19 vaccine may come with mild to moderate side effects. The vast majority of these side effects, Sheffield says, are very similar to those among women who are not pregnant and may include pain at the injection site, low-grade fever, chills, muscle aches, headaches or a combination of these symptoms. Side effects mostly occur after the second dose, and usually disappear within a few days.

Pregnant women may experience changes in their immune systems that can make them more vulnerable to respiratory viruses, such as SARS-CoV-2 which causes COVID-19. This, says Sheffield, means expectant mothers should be proactive regarding safety measures.

“If you’re pregnant, you should take precautions to protect yourself from getting COVID-19, including physical distancing, wearing a mask, hand-washing and staying in close communication with your health care provider — even after vaccination,” she says.

Sheffield adds that it’s important to understand that the initial COVID-19 vaccine clinical trials did not evaluate their effectiveness and safety for pregnant women. However, she says preliminary developmental and reproductive toxicity studies do not indicate any adverse effects on reproduction or fetal development. She says more data from additional studies will be available in the coming months that should better address these issues.

While there are still many unanswered questions about the COVID-19 vaccines for pregnant women, Johns Hopkins Medicine agrees with and supports the recommendations of the U.S. Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices, the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine.

“We know that SARS-CoV-2 adversely affects pregnant women and that is one of the main reasons why we’re supportive of vaccinating them against COVID-19,” says Sheffield.

Sheffield is available for interviews.