Seattle, WA–Now that the is pushing even harder to get pregnant women vaccinated against COVID-19, data on rates of side-effects can provide some reassurance.

The University of Washington Medicine survey of more than 17,000 pregnant and lactating individuals who received the COVID-19 vaccine indicates that expectant mothers did not experience symptoms any more severe than their nonpregnant counterparts.

Results, published in JAMA Network Open, showed “there were not any increased reactions in pregnant individuals beyond what is expected from a vaccine,” said senior author Linda Eckert, MD, a professor of obstetrics and gynecology at the University of Washington School of Medicine.

“Pregnant people do well with the vaccine,” added lead author, Alisa Kachikis, MD, MSC.

The CDC recently recommended that all pregnant women get vaccinated against the virus, pointing out that only 23% of U.S. pregnant women were vaccinated as of the end of July, with the lowest rates among Black and Latina women.

Based on research finding that COVID-19 is associated with adverse events in pregnancy, SARS-CoV-2 vaccines are urged for pregnant and lactating women, even though those cohorts weren’t included in clinical trials, according to the report. The authors advise, however, that little has been documented on the experiences of pregnant and lactating individuals after receiving COVID-19 vaccines.

To remedy that, the study team launched an online prospective cohort study in January, targeted at adults primarily located in the United States who were pregnant, lactating, or planning pregnancy at the time of COVID-19 vaccination.

Participants who were recruited and enrolled online in the UW COVID-19 Vaccine in Pregnancy and Lactation Registry were invited to participate and electronic written informed consent was obtained. Data were analyzed from January through March 2021.

As of March 16, 2021, about 17,400 patients, 99.7% women with a mean age of 33.6 and 87.6% white had enrolled in the survey. Their pregnancy status was known, and they had all received at least one dose of a COVID-19 vaccine, with 85.9% getting two doses.

Of those, 44.6% were pregnant, 38.7% were lactating and 16.5% who were neither but were planning pregnancy in the near future when they received their first vaccine dose. Most, 61.9%, received the Pfizer-BioNTech BNT162b2 vaccine, followed by 37.8% who got the Moderna mRNA-1273 vaccine. In addition, most participants lived in the U.S., were employed in healthcare, and had completed some college education.

Most of the participants, 97.0%, reported any postvaccination reactions after the first dose, with the most common reactions being pain at injection site in 91.4% and fatigue in 31.3%.

Researchers report that the frequency of reactions after the second dose was higher than after the first dose but similarly distributed.

“Odds of several reactions were statistically significantly decreased among individuals who were pregnant (e.g., fever after BNT162b2 dose 2: OR, 0.44; 95% CI, 0.38-0.52; P <.001 and after mRNA-1273 dose 2: OR, 0.48; 95% CI, 0.40-0.57: P <.001) compared with individuals who were neither pregnant nor lactating,” the authors write.

The study team points out that, among pregnant participants, any obstetrical symptoms were reported by 4.4% after the first dose and 7.5% after the second dose.

By the time of data analysis, 94.8% who reported two vaccines were still pregnant, 4.3% had delivered and 0.7% had suffered miscarriage, according to the researchers. Among those breastfeeding, 2.3% had to interrupt lactation after the first dose and 2.2% had to do so after the second dose. Reasons ranged from decreased milk supply for less than 24 hours and concerns about how the infant would be affected.

“We hope that this data will be another reassuring piece of information ... about why pregnant individuals need to get vaccinated against COVID-19,” Dr. Eckert noted. "Not only is the vaccine safe, our research shows just how well the vaccine is tolerated in pregnant individuals—which is a common fear I hear from my patients. In contrast, we are continuing to learn more and more about just how dangerous COVID-19 infections are in pregnancy.”

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

 « Click here to return to Weekly News Update.