Ultrasound Study Shows No Link Between COVID-19 Vaccines and Birth Defects

Preliminary ultrasound findings from a study of over 3,000 women in early pregnancy found no association between fetal anomalies and initial COVID-19 vaccination.

For women in early pregnancy, emerging research suggests there is no link between initial dosing of COVID-19 vaccines and fetal structural anomalies.

The cohort study was comprised of 2,622 pregnant women who received at least one dose of a COVID-19 vaccine and 534 unvaccinated pregnant women. Second trimester ultrasound exams revealed fetal structural anomalies in 27 unvaccinated women (5.1 percent) in comparison to 109 women who had at least one vaccine dose (4.2 percent), according to preliminary study findings, published in a research letter in JAMA Pediatrics.

“Our findings suggest that COVID-19 vaccination during early pregnancy is not associated with an increased risk of fetal structural anomalies identified with ultrasonography,” wrote Emily S. Miller, MD, MPH, an assistant professor of obstetrics and gynecology and psychiatry and behavioral sciences with Northwestern University’s Feinberg School of Medicine, and colleagues.

The researchers looked at COVID-19 vaccine administration within and outside of a teratogenic window, which ranged between 30 days prior to conception to 14 weeks of gestation. The study authors noted that 1,149 women received a vaccine dose within the teratogenic window and 1,473 women had the vaccine dose outside of the teratogenic window. Comparing these groups with women who were either unvaccinated or vaccinated outside of the teratogenic window, Dr. Miller and colleagues found similar rates of fetal structural anomalies across all study participants within the teratogenic window and at two to 10 weeks of gestation, according to the study.

Dr. Miller and colleagues said these preliminary findings could be beneficial for clinicians who may be fielding questions about the safety of getting COVID-19 vaccines during early pregnancy.

In regard to study limitations, the study authors noted the data were derived from a single center in a retrospective design. Dr. Miller and colleagues also emphasized the surrogate outcome nature of ultrasonography measures with many of the study participants having ongoing pregnancies.