Maternal exposure to extreme high-temperature, particulate air pollution and macrosomia in 14 countries of Africa.

Background: Macrosomia has increased rapidly worldwide in the past few decades, with a huge impact on health. However, the effect of PM and extreme high-temperature (EHT) on macrosomia has been ignored.

Objective: This study aimed to explore the association between maternal exposure to EHT, PM and macrosomia based on the Seventh Demographic and Health Survey (DHS) in 14 countries of Africa.

Methods: The study included detailed demographic information on 106 382 births and maternal. Satellite inversion models estimated monthly mean PM and mean surface temperature of 2 m (SMT ). Macrosomia was defined as the birth weight ≥ 4000 g. We used a Cox proportional risk regression model to estimate the association between PM , EHT and macrosomia. We further explored the susceptibility of exposure to EHT and PM at different pregnancy periods to macrosomia, and plotted the expose-response curve between PM and macrosomia risk using a restricted cubic spline function. In addition, the Interplot model was used to investigate the interaction between EHT and PM on macrosomia. Finally, some potential confounding factors were analysed by stratification.

Results: There was the positive association between EHT, PM and macrosomia, and the risk of macrosomia with the increase in concentrations of PM without clear threshold. Meanwhile, EHT and PM had a higher effect on macrosomia in middle/later and early/middle stages of pregnancy, respectively. There was a significant interaction between EHT and PM on macrosomia.

Conclusions: Maternal exposure to EHT, PM during pregnancy was associated with an increased risk of macrosomia in Africa.