By Dr Sylvester Dodzi Nyadanu and Professor Gavin Pereira, Perinatal and Environmental Epidemiologists, Curtin University
Gestational age is a key factor in determining the health of a newborn, but could climate change influence when babies are born?
A new study suggests that exposure to air pollution and extreme weather conditions during pregnancy may not only trigger preterm birth but could also prolong pregnancy, with potential health risks for both mother and baby.
Pregnancy length and health implications
Preterm birth – born before 37 weeks – has been widely studied, with known risk factors including maternal health, socioeconomic status, and environmental factors such as heat and cold waves and poor air quality.
However, little attention has been given to prolonged pregnancy – born beyond 41 weeks – despite its own set of complications, including increased risk of stillbirth, birth trauma, caesarean delivery, pregnancy complications, postpartum haemorrhage, and childhood behavioural, emotional, and developmental disorders.
Climate exposure and prolonged pregnancy
The study looked at the association between climate-related exposures and prolonged pregnancy, analysing nearly 400,000 births in Western Australia between 2000 and 2015 using data from the Western Australian Midwives Notification System.
It also used satellite data to assess levels of fine particulate air pollution (PM2.5) and a biothermal stress index – a combined index of air temperature, radiant temperature, humidity, wind speed, and human physiology.
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After adjusting for maternal and foetal risk factors, it was found that exposure to higher levels of air pollution and extreme biothermal stress (heat and cold) during pregnancy was associated with an increased risk of prolonged pregnancy.
Certain groups were more vulnerable, including first-time mothers, those over 35-years-old, women living in urban areas and those with pregnancy complications.
Out of 47,380 cases of prolonged pregnancy in the study, an estimated 2,085 cases (4.4%) were attributable to air pollution levels above the World Health Organization’s recommended annual limit of 5μg/m3, while 853 cases (1.8%) were attributed to high biothermal stress.
How could this happen?
The exact mechanism explaining how climate-related exposures could affect health outcomes, including adverse pregnancy outcomes, is unknown.
However, some of the direct ways by which climate-related exposures may influence pregnancy length are through factors such as oxidative stress, inflammation, disruptions to endocrine or hormonal function, and epigenetic programming.
These could either trigger early labour, resulting in preterm birth, or extend gestation beyond the normal timeframe, resulting in prolonged pregnancy.
Implications for healthcare and policy
As climate change events increase in duration, frequency, and intensity, the findings, together with existing evidence, raise important questions about how healthcare systems can better support pregnant women in adapting to environmental risks.
Integrating climate-related health risks into prenatal care, particularly for vulnerable groups, and implementing public health interventions to build resilience against climate effects should be considered to promote a healthy pregnancy.
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The findings also serve as a call to action for broader climate policies. Given the increasing pace of climate change and its effects on human health, ensuring pregnant women have access to clean air and protection from extreme weather should be a priority for policymakers.
This reinforces the need for climate action at every level – individual, community and government – to safeguard the health of present and future generations.
Key messages
- Climate change events such as air pollution and extreme weather impact pregnancy outcomes
- Air pollution and extreme weather can lead to preterm or prolonged births
- Climate actions across all levels – individual, community, government, and healthcare system – are essential to reduce related health risks.
Author competing interests: Both authors were involved in the Curtin University study.
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