(Adrienne Gordon, Camille Raines-Greeno and Ollie Jay, University of Sydney)
Heat Pregnancy Risk: Sydney, As we continue to face the effects of climate change, the frequency and intensity of heat waves is increasing. We recently learned that 2023 was the hottest year on record.
Extreme heat poses a major public health risk. This can be particularly dangerous for people who are socio-economically disadvantaged, and people whose physical ability to adapt is reduced, such as the elderly and people with certain medical conditions.
Pregnant mothers are also vulnerable, with evidence showing that exposure to extreme heat increases the risk to the baby.
What are the risks?
Globally, one stillborn baby is born every 16 seconds and every year 15 million babies are born prematurely (before 37 weeks of pregnancy). Complications from prematurity are the leading cause of death and disability in children under five years of age.
A systematic review that included studies from 27 countries showed that for every 1 degree Celsius increase in ambient (environmental) temperature, the risk of preterm birth and stillbirth increases by 5%.
The risk of heat-related stillbirth and preterm birth is higher in low- and middle-income countries, where women often perform agricultural or other manual labor tasks, and their work continues until the end of their pregnancy. The risk is higher among disadvantaged populations in high-income countries.
Recent Australian research also suggests that maternal exposure to extreme temperatures may affect a baby’s birth weight.