In the largest systematic review of its kind, we reviewed 198 studies that assessed the impact of heat on maternal, fetal, and neonatal health, across 66 countries.

We found that for every 1°C increase in heat exposure, there was a 4% increase in odds of preterm birth across all the studies. During a heatwave, the odds of preterm birth increased by 26%. Similarly, we found marked increases in other adverse outcomes such as increased risk for gestational diabetes, stillbirths, congenital anomalies and obstetric complications with increasing exposure to heat. There is limited research on outcomes like antenatal bleeding and caesarian section risks that may be related to heat exposure and could contribute significantly to morbidity and mortality.

“Our research provides compelling evidence that heat exposure poses severe health risks for pregnant women and their babies, yet these risks are frequently underestimated”, said Prof. Matthew Chersich, executive director at Wits Planetary Health Research.