Researchers have found that women are more likely to have a preterm birth when exposed to extreme heat and those with pre-existing conditions may have an even higher risk.
Preterm or premature birth, when a baby is born before 37 weeks of pregnancy, is the leading cause of infant death worldwide and many children born early deal with ongoing health problems for the remainder of their lives.
The team from Women and Babies Research at the Kolling Institute and the University of Sydney examined over 918,000 births in NSW over a ten-year period.
The study found about 29,000 or 3.2 per cent of babies were born as a result of preterm birth. Importantly, researchers found that when it was hotter, the risk of preterm birth increased for all women and particularly for women with diabetes, hypertension, chronic illness and those who smoke.
On days where it was hotter than 33 degrees the risk of preterm birth increased by 12 per cent compared with a 20 degree day. This increase in risk was potentially higher for women with diabetes (29 per cent), hypertension (29 per cent), chronic illness (17 per cent) and those who smoked during pregnancy (19 per cent).
Lead study author Edward Jegasothy PhD said it was the first study to link effects of extreme weather and preterm birth in the temperate climate of New South Wales.