Name: New Study Clarifies Whether Extreme Heat is Causing Premature Births in Pakistan
Uploaded: 2026-07-18T08:10:09+00:00
Description: Extreme heat during pregnancy may have only a small and uncertain effect on premature birth in Pakistan, according to a study of 46,773 deliveries across four cities. Researchers initially found that women exposed to at least one hot and humid day above 33°C during the final trimester had around 33% higher odds of giving birth prematurely.

Extreme heat during pregnancy may have only a small and uncertain effect on premature birth in Pakistan, according to a study of 46,773 deliveries across four cities. Researchers initially found that women exposed to at least one hot and humid day above 33°C during the final trimester had around 33% higher odds of giving birth prematurely.

Extreme heat during pregnancy may have only a small and uncertain effect on premature birth in Pakistan, according to a study of 46,773 deliveries across four cities.

Researchers initially found that women exposed to at least one hot and humid day above 33°C during the final trimester had around 33% higher odds of giving birth prematurely.

However, the apparent connection almost disappeared after they accounted for differences between cities and seasonal birth patterns.

Following these adjustments, heat exposure was linked to a difference of just 0.06% in premature births, which was statistically negligible.

The study was led by Dr. Shaper Mirza of the Lahore University of Management Sciences (LUMS) and Dr. Faridah Amir Ali of the Indus Hospital and Health Network. It examined births recorded between June 2021 and July 2024 in Karachi, Lahore, Muzaffargarh, and Badin.

Overall, 25.8% of births were premature, but the rate varied significantly between cities, ranging from 13.1% in Lahore to 36% in Badin.

According to the researchers, Badin was largely responsible for the strong link seen in the initial analysis.

Nearly 96% of births in Badin were preceded by at least one hot and humid day above 33°C. The city also had the highest premature birth rate, which varied from 27.6% in November to 46.9% in August.

This meant that a basic analysis could confuse living in Badin with being exposed to extreme heat.

The researchers said Badin’s seasonal pattern could be linked to hospital referrals connected to the agricultural calendar, seasonal infections, and changes in maternal nutrition.

To test the heat effect more closely, the team used five different analytical methods on the full dataset, the dataset without Badin, and Badin’s data separately.

Two methods found no link between heat and premature birth. Two others found a connection only when Badin was included. The relationship disappeared or reversed when the city was removed.

Only one method produced a consistent result. It found that women exposed to more days of 40°C or above during the middle months of pregnancy had around 4% higher odds of premature delivery.

However, the researchers said this finding was weak. An unmeasured factor affecting both heat exposure and premature birth by as little as 5% could remove the link entirely.

A more advanced model examining delayed heat effects also found no lasting impact on premature birth.

The researchers concluded that future studies must carefully account for location and seasonal differences before linking extreme heat to premature birth.

They also recommended using multiple analytical methods and collecting more detailed information about mothers’ health, circumstances, and actual heat exposure.

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