Characteristics of preterm births during COVID‐19 mitigation measures.

Background Aim Material and methods Results Conclusion During the COVID‐19 pandemic, mitigation measures were associated with a reduction in preterm birth rates; while not clearly proven, this observation has sparked significant interest.To understand the cause of this reduction by exploring the characteristics of preterm birth cohorts.We performed a retrospective cohort study where we compared women who delivered preterm in three Melbourne maternity hospitals and conceived between November 2019 and February 2020 (mitigation measures‐exposed cohort) to women who delivered preterm and conceived between November 2018 and February 2019 (non‐exposed cohort). We compared maternal characteristics, pregnancy complications, antenatal interventions, intrapartum care, and indications for delivery.In the exposed cohort, 252/3129 women delivered preterm (8.1%), vs 298/3154 (9.4%) in the non‐exposed cohort (odds ratio (OR) 0.84, 95% CI 0.70–1.00, P = 0.051). The baseline characteristic of two cohorts were comparable. Rates of spontaneous preterm labour (sPTL) without preterm pre‐labour rupture of membranes (PPROM) were lower in the exposed cohort (13.1% vs 24.2%, OR 0.47, P = 0.001) while PPROM occurred more often (48.0% vs 35.6%, OR 1.67, P = 0.003). With a non‐statistically significant prolongation of pregnancy in the cohort exposed to mitigation measures for both sPTL without PPROM (35.4 vs 34.9 weeks, P = 0.703) and PPROM (35.6 vs 34.9 weeks, P = 0.184). The rate of spontaneous labour after PPROM was higher in the exposed cohort compared to the non‐exposed cohort (40.1% vs 24.1%, OR 2.09, P < 0.001).The reduction in preterm delivery during mitigation measures may have been driven by a reduction in spontaneous labour without PPROM, which seemed to result in more PPROM later in pregnancy. [ABSTRACT FROM AUTHOR]