Study: Pregnant Women Pass Along Protective COVID-19 Antibodies to Babies

A new study has found that antibodies that guard against coronavirus disease 2019 (COVID-19) can transfer from mothers to babies while in the womb, according to researchers from Weill Cornell Medicine and New York-Presbyterian.

Published in the American Journal of Obstetrics and Gynecology, the discovery adds to growing evidence that suggests that pregnant women who generate protective antibodies after contracting the COVID-19 virus often convey some of that natural immunity to their fetuses. The findings also support that vaccinating mothers-to-be may have benefits for their newborns, according to the study authors.

“Since we can now say that the antibodies pregnant women make against COVID-19 have been shown to be passed down to their babies, we suspect that there’s a good chance they could pass down the antibodies the body makes after being vaccinated as well,” said senior study author Yawei Jenny Yang, MD, an assistant professor of pathology and laboratory medicine at Weill Cornell Medicine, in a press release.

The research team analyzed blood samples from 88 women who gave birth at New York-Presbyterian/Weill Cornell Medical Center between March and May 2020 during the time in which New York City was the global epicenter of the pandemic. All of the women had COVID-19 antibodies in their blood, indicating that they had contracted the virus at some point, even though 58% of those women had no symptoms, according to the study authors.

Further, although antibodies were detected in both symptomatic and asymptomatic women, the researchers observed that the concentration of antibodies was significantly higher in symptomatic women. They also found that the general pattern of antibody response was similar to the response seen in other patients, confirming that pregnant women have the same kind of immune response to the virus as the larger patient population, which was not previously known due to women’s immune system changes throughout pregnancy.

In addition, the vast majority of the babies born to these women (78%) had detectable antibodies in their umbilical cord blood. The researchers said they found no evidence that any of the infants had been directly infected with the virus and all were COVID-19-negative at the time of birth, further indicating that the antibodies had crossed the placenta, the organ that provides oxygen and nutrients to a growing baby during pregnancy, into the fetal bloodstream. Newborns with symptomatic mothers also had higher antibody levels than those whose mothers had no COVID-19 symptoms, according to the study authors.

These data imply that pregnant women could pass along vaccine-generated antibodies in the same way, potentially shielding both mother and child from future infection. However, it is not yet known exactly how protective these antibodies might be or how long that protection might last.

Study co-author Laura Riley, MD, chair of the department of obstetrics and gynecology at Weill Cornell Medicine, obstetrician and gynecologist-in-chief at New York-Presbyterian/Weill Cornell, is still advising pregnant patients who decide to get vaccinated to continue to follow current safety guidelines to prevent the spread of the disease.

Follow-up investigations are enrolling pregnant women who receive the vaccine, as well as vaccinated mothers who are breastfeeding, to assess the antibody response in these groups after vaccination. This information could help guide maternal vaccination strategies moving forward, according to the study authors.

REFERENCE

Researchers learn that pregnant women pass along protective COVID antibodies to their babies. Weill Cornell Medicine. https://news.weill.cornell.edu/news/2021/02/researchers-learn-that-pregnant-women-pass-along-protective-covid-antibodies-to-their. Published February 22, 2021. Accessed February 24, 2021.