Risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy: population based retrospective cohort study

Abstract

Objective To assess the risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy. Design Population based retrospective cohort study. Setting Ontario, Canada, 1 May to 31 December 2021. Participants All liveborn and stillborn infants from pregnancies conceived at least 42 weeks before the end of the study period and with gestational age ≥20 weeks or birth weight ≥500 g. Main outcome measures Using Cox regression, hazard ratios and 95% confidence intervals were estimated for preterm birth before 37 weeks (overall and spontaneous preterm birth), very preterm birth (<32 weeks), small for gestational age at birth (<10th centile), and stillbirth. Vaccination against covid-19 was treated as a time varying exposure in the outcome specific risk window, and propensity score weighting was used to adjust hazard ratios for potential confounding. Results Among 85 162 births, 43 099 (50.6%) occurred in individuals who received one dose or more of a covid-19 vaccine during pregnancy—42 979 (99.7%) received an mRNA vaccine. Vaccination during pregnancy was not associated with any increased risk of overall preterm birth (6.5% among vaccinated v 6.9% among unvaccinated; adjusted hazard ratio 1.02, 95% confidence interval 0.96 to 1.08), spontaneous preterm birth (3.7% v 4.4%; 0.96, 0.90 to 1.03), or very preterm birth (0.59% v 0.89%; 0.80, 0.67 to 0.95). No increase was found in risk of small for gestational age at birth (9.1% v 9.2%; 0.98, 0.93 to 1.03) or stillbirth (0.25% v 0.44%; 0.65, 0.51 to 0.84). Findings were similar by trimester of vaccination, mRNA vaccine product, and number of doses received during pregnancy. Conclusion The findings suggest that vaccination against covid-19 during pregnancy is not associated with a higher risk of preterm birth, small for gestational age at birth, or stillbirth.

The impact of maternal SARS-CoV-2 infection and COVID-19 vaccination on maternal-fetal outcomes

“…There have now been several large population studies that examine the impact of COVID-19 vaccination on birth outcomes. [19] , [20] , [45] , [65] , [66] , [67] , [107] , [108] , [109] , [110] , [111] Lower rates of very preterm birth (<32 weeks gestation) was observed in vaccinated pregnant people in Ontario, Canada (34% reduction) and Sweden (22% reduction), [67] but no difference was observed in Norway. [67] Several studies reported no association of vaccination status with preterm birth, stillbirth, small for gestational age, very low birth weight, infant mortality, or neonatal hospitalizations.…”

“… [67] Several studies reported no association of vaccination status with preterm birth, stillbirth, small for gestational age, very low birth weight, infant mortality, or neonatal hospitalizations. [19] , [20] , [45] , [65] , [66] , [67] , [106] , [107] , [108] , [110] , [111] Two studies reported 40-43% reductions in the rate of stillbirth in vaccinated people and the effect remained even after adjusting for common cofactors. [20] , [110] Another reported a slight decrease in risk for NICU admission in babies born to people receiving at least one-dose compared to those born to unvaccinated people.…”

“…[19] , [20] , [45] , [65] , [66] , [67] , [106] , [107] , [108] , [110] , [111] Two studies reported 40-43% reductions in the rate of stillbirth in vaccinated people and the effect remained even after adjusting for common cofactors. [20] , [110] Another reported a slight decrease in risk for NICU admission in babies born to people receiving at least one-dose compared to those born to unvaccinated people. [109] .…”

Vaccine effectiveness for preventing COVID-19 hospital admission during pregnancy: a population-based cohort study in England during the Alpha and Delta waves of the SARS-CoV-2 pandemic

“…[41] Other studies have shown a lower risk of stillbirth in those vaccinated, and no evidence for adverse pregnancy outcomes following COVID-19 vaccination. [12, 42] Vaccination coverage among women giving birth has been increasing over time, but uptake remains lower at the time of delivery in women from ethnic minority groups, with lowest vaccination rates in black women, and those living in deprived areas. [11] Interventions to address these inequalities and engagement with pregnant women to ensure uptake of future booster vaccines are needed, since many women who become pregnant may have received their last dose of a vaccine several months previously.…”

The best response to US criminalisation of abortion is decriminalisation elsewhere

“…Abortion, of course, isn’t the only medical issue where the voice of the evidence is lost amid populist clamour and political opportunism. This week’s examples are the “zombie policy” of user charges for missed appointments 9 and introducing prostate cancer screening under the guise of “case finding.”10 Isolating the evidence signals from the noise–whether it is about the safety of covid vaccines in pregnancy,11 the new clinical features of monkeypox,1213 or how best to limit sitting time in office based work 14–is as much a responsibility of policy and law makers as it is of clinicians.…”