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Pregnant Women More Likely To Give Birth Early During A Heat Wave

Section: Pregnancy

Experts have found that heavily pregnant women are more likely to give birth early when temperatures reach 32C for three or more days.

Researchers from the University of Montreal looked at data from 300,000 births in the city from 1981 to 2010 and compared them against summer temperatures recorded at the same time.

When the hot weather stayed for between four and seven days, the risk of early labour increased to 27 per cent.

While the research, published in the journal Epidemiology, showed that consistent high temperatures didn’t increase the number of babies born before 37 weeks, the researchers found that women who were 37 or 38 weeks pregnant were 17 per cent more likely to give birth if the temperature stayed at 32C for three days or more.

When the hot weather stayed for between four and seven days, the risk of early labour increased to 27 per cent.


‘Studies suggest that heat-induced stress increases uterine contractility, during a period of pregnancy when thermoregulation seems less effective,’ says the study’s lead author Dr Nathalie Auger.

‘We also suspect that dehydration reduces blood supply to the uterus, increasing the release of pituitary hormones that induce labour.’


If you’re due to give birth this summer, make sure you don’t overdo it and look after yourself. Drink plenty of water and stay in the shade whenever possible to avoid the risk of overheating.

If you’re expecting a baby, how are you keeping cool in the heat? Share your tips in the comments box below.

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