As activists around the world raise awareness about climate change, a new study published in Nature Climate Change has found rising temperatures to have a direct impact on human gestational time period.
The study suggests that climate change could increase the risk of early delivery, before 40 weeks. Extreme heat, among other factors, could cause an otherwise healthy pregnancy to come to term earlier than it should.
To analyse this, Alan Barreca, associate professor at UCLA’s Institute of Environmental Sustainability, and economist Jessamyn Schaller of Claremont McKenna College studied daily temperature and county-by-county birth rates across the US, between 1968 and 1988.
Talking about the data, Barreca said, “In 1989, the vital statistics system started to be more cautious about information it allowed out publicly in order to make it hard to identify individuals precisely by place or date of birth. They even began masking some counties. So 1969 to 1988 gave us the most thorough information.”
The study found that on days when the temperature reached or exceeded 32.2 degrees Celsius, the birth rate per 100,000 women increased by 0.97, compared to days when the temperature was recorded between 16-21 degrees Celsius. On days with temperature between 26.7-32.3 degrees Celsius, researchers found a small but significant 0.57 additional births per 100,000 women.
The study suggests that heat could lead to cardiovascular stress in the mother thereby inducing early labour. The other possibility is that higher temperatures could lead to an increase in the levels of the hormone oxytocin that plays a role in labour and lactation. The third possibility could also be lack of sleep and discomfort due to high temperatures, suggested Barreca.
The effect of heat on pregnancy, however, was comparatively lesser in pregnant women from warm weather regions since they are acclimated to high temperature. Air condition, on the other hand, could further reduce the impact.
On average, however, Barreca and Schaller calculated that an early birth caused by 32.2 degrees Celsius or greater temperature cost a woman and her baby 6.1 days of gestation.
It is important to note that the study compared results from couple of decades earlier while today, climate change is getting more severe each day, at almost a “point of no return” as mentioned by UN Secretary General Antonio Guterres.