Spontaneous abortion after COVID-19 vaccination during pregnancy

Kharbanda EO, Haapala J, DeSilva M, et al. Spontaneous abortion after COVID-19 vaccination in pregnancy. Jama. 2021; 326(16): 1629-1631. doi: 10.1001 / jama.2021.15494

Commentary

This study incorporated diagnosis and procedure codes, electronic health record (EHR) data, and assigned a validated pregnancy algorithm to be applied to identify spontaneous abortions and weeks in gestation.

Data 2021 from eight health systems (Kaiser Permanente: Washington, Northwest, Northern California, Southern California, Colorado, Denver Health, HealthPartners, and Marshfield Clinic, Wisconsin) over a four-week monitoring period from December 15, 2020 to June 28, 2020 were included.

Ongoing pregnancies between 6 and 19 weeks of gestation were identified on the last day of each 4-week surveillance period and provided data for one or more surveillance periods. Spontaneous abortions were assigned to a 4-week surveillance period based on the date of the outcome. Immunization data were obtained from EHRs, medical and pharmacy claims, and local or state immunization information systems.

Of the 105,446 pregnancies, 13,160 spontaneous abortions and 92,286 ongoing pregnancies were identified. Overall, 7.8% of the women had received one or more BNT162b2 (Pfizer-BioNTech) vaccines.

6.0% received one or more mRNA-1273 (Moderna) vaccine and 0.5% received Ad26.COV.2.S (Janssen) vaccine during and before 20 weeks of pregnancy.

The percentage of women between the ages of 35 and 49 years with spontaneous abortions is shown to be higher than that of ongoing pregnancies (22.3%). (38.7%) COVID-19 vaccine was administered within 28 days prior to the index date in 8.0% of ongoing pregnancies and 8.6% of spontaneous abortions. Spontaneous miscarriage did not increase the odds of exposure to COVID-19 vaccination in the previous 28 days when compared with ongoing pregnancy. (Adjusted odds ratio, 1.02; 95% CI, 0.96-1.08)