Are COVID-19 mitigation measures reducing preterm birth rate in China?

OBJECTIVE: Preterm birth is the leading cause of child morbidity and mortality globally. We aimed to determine the impact of the COVID-19 mitigation measures implemented in China on 23 January 2020 on the incidence of preterm birth in our institution. DESIGN: Logistic regression analysis was used to investigate the association between the national COVID-19 mitigation measures implemented in China and the incidence of preterm birth. SETTING: Shanghai First Maternity and Infant Hospital, Shanghai China. PARTICIPANTS: All singleton deliveries abstracted from electronic medical record between 1 January 2014 to 31 December 2020. MAIN OUTCOME MEASURES: Preterm birth rate. RESULTS: Data on 164 107 singleton deliveries were available. COVID-19 mitigation measures were consistently associated with significant reductions in preterm birth in the 2-month, 3-month, 4-month, 5-month time windows after implementation (+2 months, OR 0.80, 95% CI 0.69 to 0.94; +3 months, OR 0.83, 95% CI 0.73 to 0.94; +4 months, OR 0.82, 95% CI 0.73 to 0.92; +5 months, OR 0.84, 95% CI 0.76 to 0.93). These reductions in preterm birth were obvious across various degrees of prematurity, but were statistically significant only in moderate-to-late preterm birth (32 complete weeks to 36 weeks and 6 days) subgroup. The preterm birth difference disappeared gradually after various restrictions were removed (7th–12th month of 2020, OR 1.02, 95% CI 0.94 to 1.11). There was no difference in stillbirth rate across the study time window. CONCLUSION: Substantial decreases in preterm birth rates were observed following implementation of the national COVID-19 mitigation measures in China. Further study is warranted to explore the underlying mechanisms associated with this observation.