Abstract:
Complications of preterm birth is the leading cause of deaths in newborns and children under the age of 5 years. Epidemiological evidence indicates that maternal exposure to ambient temperature extremes is associated with a higher risk of preterm birth, but the relationships between different kinds of ambient temperature extremes (heat, cold, and temperature variation) and preterm birth are still unclear. In the climate change context, the frequency and intensity of temperature extremes will increase; therefore, the impacts and pathways of exposure to extreme temperature events during pregnancy on preterm birth require to be elucidated, so as to provide scientific guidance for pregnant women against the health hazards of temperature extremes. Through reviewing epidemiological evidence on associations of preterm birth with heat, cold, and temperature variation, we found current studies mainly focused on heat; i.e., exposure to heat (>
P90 of daily mean temperature) during pregnancy increased the risk of preterm birth, and the effect was modified by exposure window, regional climate, and maternal health. However, evidence on the risk of preterm birth caused by cold (<
P10 of daily mean temperature) and temperature variation was limited and inconsistent. In the future, more efforts on the research of exposure-response relationship between temperature extremes and preterm birth among mothers at different gestational ages, in regions with different climate regimes, and for different populations, and pathways of temperature extremes leading to preterm birth are urgently needed for developing clinical interventions to reduce the risk of preterm birth.