Soaring temperatures are increasing birth complications and defects in newborns, a new report has warned.

The report, which surveyed 1,000 doctors and midwives, found that at least 73 per cent of healthcare workers across Australia, Brazil, Britain, India and Zimbabwe had seen an uptick in heat-related complications in pregnancy and birth.

High temperatures can cause surface-level blood vessels to dilate, which in pregnant women can significantly decrease blood flow to the placenta and reduce oxygen and nutrients reaching the foetus.

This phenomenon can increase the risk of stillbirth, premature births, and low birth weight, the report, released by the Wellcome Trust, said.

Heat can also make it hard for newborn babies, whose bodies are already extremely fragile, to regulate their internal temperatures – which can significantly impact both their ability to breathe properly and feed from their mothers.

Extreme heat can also severely affect the health of a pregnant woman, placing heavy demands on the…