Pregnant or Breastfeeding? New Study Sheds Light on Safety of COVID-19 Vaccines.

Sujal Mandavia, MD
April 9, 2021

People who are pregnant or nursing may be unsure about whether to get the COVID-19 vaccine, in part because early research into the safety of the vaccines did not involve pregnant women. Nonetheless, medical professionals are advising patients who are pregnant and lactating to get the vaccine because, while more evidence around safety is needed, there isn’t mounting evidence of adverse effects. And now one small study, recently published in the American Journal of Obstetrics and Gynecology, may provide a bit more assurance. 

About the Study

The published study evaluated 131 women who were given either the Pfizer or the Moderna vaccine. In the small group, 84 women were pregnant, 31 were lactating, and 16 were between the ages of 18 and 45 years old and not pregnant. The patients came from three medical institutions: Brigham and Women’s Hospital, Massachusetts General Hospital, and Ragon Institute, an immune system research collaboration with support from Harvard, MIT, and Massachusetts General Hospital.

Blood samples were collected from each patient at the time of their first and second vaccine doses and then six weeks after their second dose. Antibody levels were compared among the three patient populations and then compared with data from pregnant women who had natural antibodies produced after COVID-19 infection.

What the Study Revealed

The study found that the vaccine-induced antibodies in pregnant and lactating women were comparable to the non-pregnant women who were vaccinated. At the same time, all of the vaccinated women showed higher levels of antibodies when compared with pregnant women who had COVID-19 and produced natural antibodies.

The study also revealed that the baby may enjoy immune benefits from the vaccines as well. Vaccine-generated antibodies were found in umbilical cord blood and breast milk samples.

Digging deeper into the data involving the pregnant and lactating women in the study, the researchers found that the second dose of each vaccine increased levels of the SARS-CoV-2-specific IgG (Immunoglobulin G) antibody — the most common bacteria and virus-fighting antibody your body produces. But it did not increase levels of IgA (Immunoglobulin A), another critical immune antibody that functions in your mucous membranes. However, no other significance tied to patient health outcomes was found with regards to that data. In addition, no adverse reactions or differences in side effects were seen among pregnant or lactating women taking the vaccine when compared with other populations.

The overall conclusion is that the vaccine-induced response for these populations is “significantly greater,” according to the study’s authors, than the immune response to natural infection. And there’s also the added benefit of immunity transferring neonatally through placenta and breast milk.

More to Come

These results are encouraging, but the medical community acknowledges that the study included only a small sample of women. The question of whether the vaccine is safe for mother and child is further complicated by a slightly increased chance of severe illness or death if a pregnant woman is infected with COVID-19. More research is on the horizon that, hopefully, will further validate the study’s findings. Pfizer has initiated a study involving 4,000 women.

In the meantime, the CDC is collecting its own data. If you are pregnant or lactating and have made the decision to vaccinate, you can sign up for the CDC’s V-Safe Pregnancy Registry. Your information is confidentially held in a database, and tracking the health and outcomes of this population is helpful for future research and evaluation.

We’re all learning a lot very quickly with regards to COVID-19’s spread and the efficacy of the vaccines on different populations. This study represents a positive step and another important piece of data for medical professionals to consider when recommending the vaccine to their patients.

The vaccine roll-out has seen tremendous success so far. But even if you have been vaccinated, it’s recommended that you remain cautious and continue to follow all safety practices such as social distancing and mask wearing, especially if you know you’re around others who may not be vaccinated. Many of us in the medical community are confident more research will continue to support claims of vaccine safety and efficacy, but it’s important for all of us to stay patient and do our part to keep ourselves and others safe until the CDC knows the virus is fully under control.

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Carbon Health’s medical content is reviewed and approved by healthcare professionals before it is published. But note that our knowledge and understanding of COVID-19 are developing and changing very rapidly; if you have questions or concerns about COVID-19 precautions, treatments, and vaccinations, please talk to your healthcare provider.

Sujal Mandavia, MD

Dr. Mandavia has over 20 years of healthcare management experience. In his role as Chief Medical Officer at Carbon Health, Mandavia oversees all clinical operations and protocols, as well as the expansion of Carbon Health's world-class clinical care offering. When not at work, Sujal enjoys everything hockey related, listening to the Tragically Hip, and being taken for hikes by his Rhodesian Ridgebacks.