No link to spontaneous abortion
The results of a case-control surveillance of COVID-19 vaccination during pregnancy and spontaneous abortion revealed that spontaneous abortions did not increase following COVID-19 vaccinations, according to Elyse O. Kharbanda, MD , MPH, HealthPartners Institute, Minneapolis, Minnesota, first author of the study.1
According to investigators, this is good news given the severe maternal morbidity associated with COVID-19 infection during pregnancy.2
Investigators included data from 8 health systems over 7 4-week surveillance periods from December 15, 2020 to June 28, 2021.
A validated pregnancy algorithm was used which included diagnostic and procedural codes and electronic health record data to identify and assign gestational ages for spontaneous abortions and ongoing pregnancies; immunization data came from electronic health records, medical and pharmaceutical claims, and regional / state immunization systems.
Pregnancies between 6 and 19 weeks gestation were identified on the last day of each 4-week surveillance period (index date). Spontaneous abortions were assigned a 4-week monitoring period based on their outcome date.
The authors analyzed the odds of receiving a COVID-19 vaccine within 28 days before a spontaneous abortion versus the odds of receiving a COVID-19 vaccine within 28 days before index dates for current pregnancies.
Spontaneous abortions and ongoing pregnancies were attributed to gestational age groups 6-8, 9-13 and 14-19 weeks), surveillance periods, site, maternal age groups (16-24 , 25-34 and 35-49 years), number of antenatal visits (≤1 or ≥2), and race and ethnicity.
A total of 105,446 pregnancies were recorded; of these, 13,160 spontaneous abortions occurred and 92,286 pregnancies continued.
Almost 7.8% of women received 1 or more BNT162b2 vaccines (Pfizer-BioNTech); 6.0% 1 or more mRNA-1273 vaccines (Moderna); and 0.5% the Ad26.COV.2.S vaccine (Janssen) during pregnancy and before 20 weeks of gestation. More women aged 35 to 49 had a spontaneous abortion (38.7%) compared to those with an ongoing pregnancy (22.3%).
“A COVID-19 vaccine was received in the 28 days preceding an index date among 8.0% of current pregnancy periods against 8.6% of spontaneous abortions.
Spontaneous abortions did not have an increased risk of exposure to COVID-19 vaccination in the previous 28 days compared to ongoing pregnancies (adjusted odds ratio, 1.02; 95%[confidenceinterval096-108)[confidenceinterval096-108)[intervalledeconfiance096-108)[confidenceinterval096-108)
The results were consistent for mRNA-1273 and BNT162b2 and by gestational age group, ”the authors reported.
Too few women have received the Ad26.COV.2.S vaccine to analyze the risks of association with spontaneous abortions.
The authors concluded that despite some limitations of the study, they believe the data can be used to advise patients on COVID-19 vaccination.
1. Kharbanda EO, Haapala J, DeSilva et al. Spontaneous abortion following COVID-19 vaccination during pregnancy. JAMA Published online September 8, 2021. doi: 10.1001 / jama.2021.15494
2. Ko JY, DeSisto CL, Simeone RM et al. Adverse pregnancy outcomes, maternal complications, and serious illness among delivery hospitalizations in the United States with and without a diagnosis of coronavirus disease 2019 (COVID-19). Clin Infect Dis 2021; 73 (suppl 1): S24-S31. doi: 10.1093 / cid / ciab344