Heat exposure and perinatal mortality: A time-stratified, case-crossover study from 16 hospitals in Benin, Malawi, Tanzania and Uganda

Abstract Extreme heat events affect both pregnant women and their infants. We applied a time-stratified case-crossover design including 124,819 singleton births in a prospective observational study in 16 hospitals in Benin, Malawi, Tanzania, and Uganda to investigate the association between extreme heat and timing of perinatal death. We observed weak associations between heat exposure and perinatal mortality with an odds ratio of 1.22 (95%CI 0.85-1.73) for stillbirths; 1.10 (95%CI 0.51-2.34) for antepartum and 1.54 (95%CI 0.63-3.73) for intrapartum stillbirths; and 1.17 (95%CI 0.84-2.61) for perinatal deaths with an increase from 75th to 99th percentile in mean temperature one week (lag 0-6 days) before childbirth. The cumulative exposure-response curve suggested the steepest slope for heat was in intrapartum stillbirths, and stronger associations during the hottest seasons. We conclude that higher temperatures may have short-term effects on mortality risks, particularly for intrapartum stillbirths, raising the importance of improved intrapartum care.