Risk of perinatal death and preterm birth among an observational cohort of women vaccinated against SARS-CoV-2 in pregnancy: CDC COVID-19 vaccine pregnancy registry.

BACKGROUND

COVID-19 vaccine clinical trials excluded pregnant women; additional data on safety of COVID-19 vaccines in pregnancy can strengthen clinical recommendations.

OBJECTIVE

To assess risk of perinatal death (stillbirth and neonatal death), and preterm birth among women receiving COVID-19 vaccines just prior to or during pregnancy.

METHODS

The Centers for Disease Control and Prevention's COVID-19 Vaccine Pregnancy Registry (C19VPR) is an observational cohort of women receiving ≥1 COVID-19 vaccine between December 15, 2020, and June 21, 2021, up to 30 days before their last menstrual period or during pregnancy. Data were collected through interviewer-administered phone surveys. We matched C19VPR pregnancies to 2019 US National Vital Statistics System (NVSS) data based on race, ethnicity, and age group. We estimated week-specific and cumulative risk of perinatal death and preterm birth using a fetuses-at-risk approach among singleton pregnancies ending ≥6 weeks' gestation. For C19VPR participants, pregnancies entered the risk pool at gestational age of vaccination. We compared C19VPR estimates to NVSS using Cox regression to calculate hazard ratios and 95% confidence intervals adjusted for race, ethnicity, age, and pre-pregnancy body mass index. Among C19VPR pregnancies, we used Cox regression to assess difference in risk by vaccine manufacturer.

RESULTS

Cumulative risk of perinatal death among C19VPR pregnancies and NVSS were 4.8 and 8.1 per 1000 births, respectively. Cumulative risk of preterm births among C19VPR pregnancies and NVSS were 6.6% and 12.1%, respectively. Adjusted hazard ratios (aHR) suggested lower cumulative risk of perinatal death and preterm birth among C19VPR pregnancies (vaccinated) compared with 2019 NVSS (pre-pandemic estimate) (aHR 0.62 95%CI 0.46, 0.83; aHR 0.55 95%CI 0.51, 0.58, respectively). Within the C19VPR cohort, risks of perinatal death and preterm birth did not differ by vaccine manufacturer.

CONCLUSION

We found no evidence of increased risk of perinatal death or preterm birth after COVID-19 vaccination in pregnancy.