[Association between exposure to non-optimal temperature during pregnancy and preterm birth]

Objectives: To investigate the effect of non-optimal temperature exposure during pregnancy on the risk for preterm birth and identify the susceptible exposure window. At the same time, the interaction between non-optimal temperature and pollutants exposure during pregnancy on preterm birth was analyzed, in order to provide strong clues for the influence of non-optimal temperature exposure during pregnancy on the risk for preterm birth. Methods: A total of 1 852 pregnant women were recruited from September 2021 to June 2023 in Fujian Provincial Maternal and Child Health Care Center. Questionnaire survey was conducted, and their health records were analyzed. The permanent address of each pregnant woman was matched with Fifth Generation European Centre for Medium-Range Weather Forecasts Atmospheric Reanalysis of the Global Climate and a geo-statistical combination model based on satellite remote sensing data collection, then follow-up for pregnancy outcome was conducted. Distributed lag nonlinear model was used to assess the association between exposure to non-optimal temperature during pregnancy and the risk for preterm birth and a multiplicative interaction model was used to assess the interaction between exposure to pollutants and non-optimal temperatures during pregnancy on the risk for preterm birth. Results: After adjusting for potential confounders such as maternal age, occupation, Gross Domestic Product of the region, pre-pregnancy preconception BMI, newborn sex, the weekly susceptibility windows of extreme low temperature (P₁, P₃, P₅) were week 1-22 , and the weekly susceptibility windows of extreme high temperature (P₉₅, P₉₇, P₉₉) were week 27 and week 32-36. Extreme low temperature [P₁ (OR=1.147, 95%CI: 1.041-1.265), P₅ (OR=1.284, 95%CI: 1.035-1.501)] and extreme high temperature [P₉₇ (OR=1.146, 95%CI: 1.039-1.263), P₉₉ (OR=1.216, 95%CI: 1.099-1.345)] exhibited multiplicative interaction with PM_2.5. Conclusions: Exposure to non-optimal temperature during pregnancy was associated with an increased risk for preterm birth. The susceptible exposure windows of extreme low temperature were mainly in early and mid-pregnancy, and the susceptible exposure windows of extreme high temperature were mainly in late-pregnancy. Exposure to non-optimal temperatures and pollutants during pregnancy was associated with an increased risk for preterm birth.