The impact of COVID-19 pandemic restrictions on pregnancy duration and outcomes in Melbourne, Australia.

OBJECTIVES: To investigate the effect of restriction measures during the COVID-19 pandemic on pregnancy duration and outcomes. METHOD(S): We conducted a before and after study with cohort sampling in three maternity hospitals in Melbourne, Australia, including women who were pregnant during the COVID-19 pandemic restriction measures (estimated conception between 1 November 2019 and 29 February 2020) and women who were pregnant before the restrictions (estimated conception between 1 November 2018 and 28 February 2019). The primary outcome was delivery before 34weeks' gestation or stillbirth. The main secondary outcome was a composite of adverse perinatal outcomes. Pregnancy outcomes were compared between the groups using chi-squared tests and modified Poisson regression models, and pregnancy duration was compared between the groups using and survival analysis. RESULT(S): There were 3150 exposed women and 3175 women in the control group. Preterm birth before 34weeks' gestation or stillbirth occurred in 95 (3.0%) of the pregnancies during restrictions and 130 (4.1%) in the control group (Risk ratio (RR) 0.74, 95% CI 0.57 to 0.96, p = 0.021). The effect was stronger in women with a previous preterm birth (RR 0.42, 95% CI 0.21 to 0.82, p = 0.008). The composite adverse perinatal outcome was less frequent in the exposed group (2.1% versus 2.9%, RR 0.73, 95% CI 0.54 to 0.99, p = 0.042 in all women and 4.5% versus 8.4%, RR 0.54, 95% CI 0.25 to 1.18, p = 0.116 in women with a previous preterm birth). CONCLUSION(S): Restrictions to mitigate COVID-19 transmission were associated with reduced rates of preterm birth before 34weeks. This effect was not associated with increased stillbirth rates and was stronger in women with previous preterm delivery. This article is protected by copyright. All rights reserved.