High Antibody Covid-19 Vaccine Response During Pregnancy and Breastfeeding

The largest study to date is more great news for pregnant people.

Pregnant women worldwide have questions about getting the Covid-19 vaccine during pregnancy. A Boston research team at Brigham and Women’s Hospital and Massachusetts General Hospital published the largest study to date verifying the efficacy of Covid-19 vaccination during pregnancy. This new study helps the 3.7 million individuals who give birth in the United States per year find an answer.

The American College of Obgyn and other Women’s health experts agree that Covid-19 vaccines should be offered to pregnant or breastfeeding people. Pregnant women were excluded from the initial Covid-19 vaccine clinical trials. Obstetrician/gynecologists, like me, follow the latest research to help our patients make safe decisions regarding their pregnancy.

The Boston research team published a study titled “Covid-19 vaccine response in pregnant and lactating women” in the American Journal of Obstetrics and Gynecology (AJOG). The paper is consistent with several small studies showing pregnant individuals have a robust immune response after the Covid-19 vaccination and secrete the antibodies into their breast milk.

This study analyzed blood samples and breast milk from 131 women in Boston and the surrounding area. The group included 84 pregnant, 31 lactating, and 16 nonpregnant individuals. The study also included five women who reported a previous SARs-CoV-2 infection. Each participant received the two-dose series of the Pfizer or Moderna Covid-19 vaccine following the FDA-approved protocols.

The research team tested blood and breast milk before vaccination and monitored the antibody response. The scientists compared antibody levels in pregnant women to 37 individuals with a history of natural infection during pregnancy and a cohort of nonpregnant people.

The results indicated a robust blood antibody response in all three groups. While scientists have shown already that moms pass protective antibodies to their baby after a natural Covid-19 infection, this study is important verification that pregnant women also develop an appropriate antibody response after vaccination.


Antibody transfer is good news for babies because a newborn’s immune system is not fully developed. Babies rely on maternal antibodies from blood and breast milk to protect against various infections during the first few months of life.

This study also reinforced encouraging news for lactating people. All the vaccinated mothers had antibodies in the breast milk samples. This finding provides further evidence that vaccinated women pass protective antibodies to their babies. Antibodies are present in breast milk within five to seven days of other viral vaccinations such as Tdap and influenza. Previous research also demonstrated women with a natural Covid-19 infection produce antibodies and secrete them into their breast milk. This study confirms published data from Portland that vaccinated women do too.

The side effects reported in the study were rare and similar in all three groups. The most common symptoms were fever and chills. These side effects are known to be good signs the vaccines are working to trigger an immune response.

Photo: Jekna Istock/Getty Images

This paper adds to the growing body of evidence supporting the safety and efficacy of Covid-19 vaccination in pregnancy and lactation. We continue to learn more about the novel coronavirus’s effects on pregnancy, newborns, and Covid-19 immunization in pregnancy.

Current research shows most pregnant people who contract Covid-19 have excellent outcomes but have an increased risk of ICU admission and preterm labor. Based on the known risks of Covid-19 infection in pregnancy, pregnant and lactating people are eligible for any one of the three Food and Drug Administration-approved vaccines.

None of the three FDA-approved vaccines contain a live virus. One cannot catch Covid-19 from the vaccine or spread the disease from the vaccines to a newborn through breastfeeding.

Pregnant patients can be confident knowing the three approved vaccines trigger an immune response to help protect themself and their babies.

Pregnant and lactating individuals are categorized as 1B in most states and1C in others.

To find a Covid-19 vaccine near you, click here.


Medika Life has provided this material for your information. It is not intended to substitute for the medical expertise and advice of your health care provider(s). We encourage you to discuss any decisions about treatment or care with your health care provider. The mention of any product, service, or therapy is not an endorsement by Medika Life

Dr Jeff Livingston
Dr Jeff Livingstonhttps://medika.life
Jeff is Co-Founder of Medika Life. He is a Board Certified Obgyn and CEO of MacArthur Medical Center in Irving, Texas. He is a nationally recognized thought leader, speaker, writer, blogger, and practicing physician who is considered an expert in the use of social media to educate patients, using new and innovative technology to improve care outcomes and the patient experience.


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