Exposure to air pollution and extreme temperatures during pregnancy could increase risk of a delay in delivery, according to an analysis of nearly four lakh births in Australia.
A prolonged pregnancy can have serious consequences for both the mother and child, with a need for medical interventions, including inducing labour. It can also increase risk of stillbirth, birth complications, and behavioural problems during early childhood.
While rising heat driven by climate change has been linked with premature births, researchers from Curtin University, Australia, said this is the first study to examine how climate exposure can affect a pregnant woman’s health.
“We know that being ‘born too soon’ — or preterm birth — has well-documented health risks, but little attention has been given to the risks associated with being ‘born too late’,” lead author Sylvester Dodzi Nyadanu, from Curtin University’s School of Population Health, said.
The findings, published in the journal Urban Climate, showed that “exposure to air pollution and biothermal stress during pregnancy increases the likelihood of prolonged pregnancies, particularly among mothers over 35 years old, first-time mothers, those living in urban areas, and those with complicated pregnancies,” Nyadanu said.
For the study, the researchers analysed data of births in the state of Western Australia. Birth records contained sociodemographic and clinical information of both mother and baby.
Twelve per cent of the births studied were found to have resulted in ‘prolonged pregnancies’.
“PM2.5 and extreme biothermal exposures increased the risk of prolonged pregnancy,” the authors wrote.
“Our findings provide the first epidemiological evidence of the associations between fine particulate matter air pollution and biothermal stress on the prolongation of pregnancy to (more than) 41 completed gestational weeks (late to post-term) with sociodemographic vulnerabilities,” the authors wrote.
Nyadanu explained that environmental stress factors, such as exposure to climate extremes, have been linked with a stress response in pregnant women, with “subsequent disruptions in endocrine and inflammatory activities, which increase towards the end of pregnancy”.
“This can either shorten gestation, leading to preterm birth, or lengthen gestation, resulting in prolonged pregnancy in some cases,” the author said.
As extreme weather events occur more often under continued warming, more studies are needed to understand how maternal and child health could be affected.
“Healthcare providers, policymakers and pregnant women — particularly those in vulnerable groups — must consider climate-related exposures when assessing pregnancy risks and planning interventions,” Nyadanu said.
Targeted policies and measures to prevent climate-related health risks, including air quality regulations and public health initiatives, are needed, the authors said.