Influence of temperature on the risk of gestational diabetes mellitus and hypertension in different pregnancy trimesters.

Previous studies have proved that exposure to extreme temperature in specific windows of pregnancy could cause some complications, such as pregnancy induced hypertension (PIH) and gestational diabetes mellitus (GDM), but differences in the effect of extreme temperature on the 2 complications are rarely studied. We carried a retrospective study on the impact of temperature on GDM/PIH in different trimesters based on data from a maternal and child health center in Beijing, China. Ambient temperatures (°C) were obtained from the China Meteorological Administration from January 1st, 2013 to May 15th, 2018. We use distributed lag non-linear models (DLNMs) combined with logistic regression to calculate the lag exposure-response relationships between the temperature and GDM/PIH from 1st to 24th/20th weeks of pregnancy. In both first and second trimesters, the risk of GDM was increased in summer with high temperatures; in second trimester, the risk of GDM increased in winter with low temperatures. In first half of pregnancy, risk of PIH was decreased in winter with low temperatures. These findings can provide the guideline for preventing the GDM and PIH induced by extreme temperature during pregnancy.