Impact of COVID-19 Lockdown on Preterm Births, Low Birthweights and Stillbirths: A Retrospective Cohort Study

Objective: The effect of lockdowns during the coronavirus (COVID-19) pandemic on pregnancy outcomes remains uncertain. We aimed to evaluate the association between the COVID-19-related lockdown and pregnancy outcomes in maternity hospitals in France. Study design: This was a retrospective cohort study from six tertiary referral hospitals in different regions of France. Three 55-day periods were compared: pre-lockdown from 22 January 2020, lockdown from 17 March 2020, and post-lockdown from 11 May 2020 to 4 July 2020. We included all women who delivered singleton or multiple pregnancies, who delivered at ≥24 weeks of gestation and with birthweights ≥500 g. We documented gestational ages at the delivery of liveborn and stillborn infants (‘stillbirths’). These were categorized as having a very low birthweight (VLBW, <1500 g), or a low birthweight (LBW, <2500 g). Adjustments were made for place of birth, maternal age, parity and diabetes, and hypertensive disorders, as well as for multiple pregnancies. Results: In total, 11,929 women delivered in the six selected centers. This figure is constituted of 4093, 3829, and 4007 deliveries in the pre-lockdown (1), peri-lockdown (2), and post-lockdown (3) periods, respectively. There were no differences in pregnancy outcomes between these three periods. Overall, birth rates <27(+6) weeks, between weeks 28(+0) and 31(+6), and between 32(+0) and weeks 36(+6) were 1.0%, 1.9%, and 4.4%, respectively. After adjustment, these rates were stable between periods 1 and 2 (adjusted odds ratio, aOR 0.90; 95% confidence interval, CI 0.69–1.19) and between periods 2 and 3 (aOR 1.04; 95% CI 0.80–1.36). Although more VLBW neonates were born during lockdown (3.5% vs. 2.6%, p = 0.03), this difference did not persist after adjustment (aOR 0.84, CI 95% 0.64–1.10). The LBW rates were similar during the three periods at 12.5% overall. The stillbirth rate was unaffected by the lockdown. Conclusion: The pregnancy outcomes (preterm birth, LBW, VLBW, and stillbirth rates) were not modified by the COVID-19 lockdown in our cohort study in France. Considering the discrepancies in results and methodological issues in previous published studies, there is not sufficient evidence to conclude that such lockdowns have any impact on perinatal outcomes.