Identifying the critical windows of temperature extremes exposure and congenital heart diseases.

The associations between atmospheric temperature and congenital heart disease (CHD) and its subtypes are still inconclusive. In this population-based retrospective case-control study, 643 CHD cases and 3,215 non-CHD controls were analyzed through distributed lag nonlinear model to estimate the effect of weekly temperature exposure on CHD risk and to identify potentially vulnerable windows. Through the binary logistic regression model, we found that elevated temperature in the first trimester was associated with an increased risk of overall CHD and ventricular septal defect (VSD) (OR: 1.059, 95% CI: 1.002-1.119; OR: 1.094, 95% CI: 1.005-1.190, respectively), while increased temperature in the second trimester was significantly positively correlated with atrial septal defect (ASD) risk. However, the results of the DLNM showed a nonlinear relationship between the weekly average temperature and the risk of total CHDs and the subtypes. Exposure to extremely, moderately, and mildly high temperatures significantly increased the risk of overall CHD, ASD and VSD, and the critical windows were mainly concentrated at the 5th-11th and 23rd-27th weeks of gestation. Low-temperature extreme exposure resulted in vulnerable windows for ASD only: 13th-14th gestational weeks. No significant positive associations were found between extreme temperature and patent ductus arteriosus or tetralogy of Fallot. In the current context of climate change, our results add new evidence to the present understanding of the effects of high- and low-temperature extreme exposure on CHD and its main subtypes.