Regions with extremely high temperatures and heatwaves are at risk of health concerns. Recent studies have also shown that pregnant women are one of the most vulnerable to heat stress. This study aims to examine whether exposure to high temperatures during pregnancy is associated with pregnancy complications.

This systematic review and meta-analysis included 175 full texts and 14,880 records that drew associations between high environmental temperatures and the risk of pregnancy complications. Pregnancy complications considered in this study were preterm birth, low birth weight, and stillbirth. The primary outcome of this study was the incidence of pregnancy complications.

The analyzed studies suggested that pregnancy complications were more common in high-temperature areas compared with low-temperature areas. Random-effects meta-analysis indicated that every 1-degree Celsius increment in temperature was associated with a 1.05-fold risk of pregnancy complication. The risk was increased by 1.16-fold during heatwaves. The most common complication was preterm birth, followed by a stillbirth. The findings further suggested that women in lower socioeconomic groups and at age extremes were at a higher risk of heat-related pregnancy complications.

The research concluded that high temperature and heatwaves were associated with a higher risk of pregnancy complications in women, with the risk being more severe in low socioeconomic groups.