Pregnancy and heat in Pakistan: Researchers seek to fill dangerous knowledge gaps

It was the beginning of spring in Karachi, and frigid mornings were giving way to balmy afternoons. But Bilal Colony was already far warmer than the rest of the city, and uncomfortably so. The eastern neighbourhood – a dense tangle of poorly ventilated homes, dusty roads and almost no green cover, tucked behind factories and car showrooms in one of Karachi’s largest industrial areas – absorbed heat differently. By afternoon, it felt several degrees warmer than neighbourhoods just a few kilometres away.

Naseem, a Bilal resident who was pregnant last spring, describes feeling suffocated in the poorly ventilated two-storey home she shares with eight others. “I felt dizzy, I couldn’t eat anything, I just wanted ice, and I couldn’t get that either because there was no electricity,” she says.

A growing body of research points to pregnant women as being among the most physiologically vulnerable to heat.

Temperatures in Pakistan routinely exceed 40C in the spring and summer, and millions live without access to reliable electricity or healthcare. Rising levels of heat are an additional stressor in a country that has one of the highest maternal mortality ratios in the world – 186 per 100,000 live births in 2019. The neonatal mortality rate was 38 per 1,000 live births in 2023, compared to 17 and 18 per 1,000 in India and Bangladesh respectively, according to data from the World Health Organisation.

Yet in Pakistan and many other low- and middle-income countries, little data exists on how heat is harming mothers and babies – the country is almost entirely absent from literature on neonatal and maternal mortality.

“The lack of research and studies in [such countries] means that we are underestimating the global burden of heat on pregnant women,” says Darshnika Lakhoo, a research clinician at Wits Planetary Health Research, an organisation focusing on the effects of climate change on public health. “Without the data and compelling arguments, [pregnant women] will never be prioritised in policy.”

For example, the disaster management authority of Pakistan’s Sindh province has standard operating procedures for heatwaves, but they contain no dedicated provisions for pregnant women. Instead, the plans depend on infrastructure that frequently fails: temporary cooling shelters in heat-prone areas; SMS and social media alerts for broadcasting heatwave warnings and precautions where women often have no mobile phone access; “cooling facilities” with air conditioning and fans in a city where electricity is often erratic. This is not specific to Pakistan: in a study published last year, researchers warn that a third of state heat action plans in India do not have any recommendations for pregnant or lactating women.

The need to fill this gap in understanding is urgent: a World Weather Attribution study found that a 2022 heatwave across Pakistan and India was made about 30 times more likely by climate change, and such events will only become more frequent as time passes.

No time to wait

“We should not wait for country-specific studies before taking action,” says Amelia Wesselink, a research assistant professor at the Boston University School of Public Health whose work focuses on heat and reproductive health.

Where local data may be lacking, high-quality studies from similar regions can be generalised to other settings, she says, while acknowledging that “what works in Karachi may be very different from what works in Boston”.

The starting point is finding out how local people experience heat, where evidence is generally limited.

“We need to start by talking to pregnant women about their experiences with heat,” Wesselink tells Dialogue Earth. “What are settings and times when they struggle to stay cool? What would be most helpful to them in those contexts?”

Since 2024, Jai Das has been working to fill those gaps in understanding in Karachi.

Das, a paediatrics research associate professor at Aga Khan University, co-authored a 2026 study which found that between 9-13% of low birth weight cases in Pakistan were attributable to heat exposure. He is also working on a first-of-its-kind study that attempts to assess the impacts of extreme heat on maternal, foetal and newborn health within Karachi and the wider Sindh province.

So far, his team have enrolled 1,200 women in the study, and aims to enrol 6,000 by the end of the year. For each woman, they are measuring biomarkers that have been historically linked with heat stress through pregnancies.

These biomarkers will help them understand the bigger pictures, says Das. “For instance, if a child is born with low birthweight, what are the pathways that have resulted in this? Understanding which biomarkers have the largest link with extreme heat will help us understand the overall impact of heat on the body.”

Exposure and equity

A key question is what interventions can help pregnant women deal with heat.

South Africa’s National Heat Health Action Guidelines identify pregnant women as a vulnerable group requiring priority interventions. They recommend community health workers be deployed to assist vulnerable populations during heat extremes. In India, city-level plans from Surat, Bhubaneswar and Rajkot include concrete steps to relocate maternity and neonatal wards away from the hottest parts of hospital buildings, and to provide education for new mothers on heat stress before they leave the hospital.

Gregory Wellenius, director of the Center for Climate and Health at Boston University, says many pregnant women in low-income countries face much larger health risks from heat than those in wealthier places. They tend to have higher exposure coupled with less access to healthcare and fewer ways of lowering temperatures. A systematic review published in November 2025 by Lakhoo and other researchers revealed that mothers in low-income countries face significantly higher risk of preterm birth due to heat.

“Many commonly recommended heat interventions assume reliable electricity, formal workplaces, and universal phone access, making them impractical for many women in low-income countries,” Wellenius tells Dialogue Earth. A fan, let alone an air conditioner, can be out of reach.

“Effective protection needs targeted, low‑tech approaches that leverage existing local community resources and are suited to the local context.”

Finding such approaches is now a priority.

Since August 2025, a group of researchers, engineers and scientists at the Aga Khan University have been trialling low-cost cooling interventions across more than 3,000 households in Karachi’s Bilal Colony and Garden West neighbourhoods, and Matiari village in Sindh province, with a specific focus on pregnant women, children and marginalised communities.

They have been installing canvas canopies that shade roofs and create spaces where women from conservative families can sit outdoors while still observing purdah (a practice that involves veiling the face in front of men who are not relatives). They have added wind-catcher ducts that funnel air into cramped homes, solar reflective paint that bounces sunlight off surfaces, and bamboo stilts with vines spread across them, which can cool narrow lanes and create communal outdoor spaces.

Anjum Naqvi, the project’s assistant manager, told Dialogue Earth he had already observed a 3-4C decrease in ambient temperature inside homes where they trialled their interventions, one per house.

He says his team feels a sense of urgency about their work. Heat has been associated with increased risk of preterm birth, low birth weight, gestational diabetes, congenital heart defects and cardiovascular events during labour.

And in Bilal Colony, where they are working, this research is a lived reality.

“We decided to focus on this [particular] neighbourhood primarily because of what happened in 2015,” Naqvi says.

That year, a heatwave drove temperatures to 45C, with the death count so high in some areas of Karachi that morgues were at capacity. Korangi district, where Bilal Colony is located, was among the hard-hit areas.

Sitting in her room, which doubles as a makeshift kitchen for the house, Naseem tells Dialogue Earth that she hopes the canvas canopy Naqvi and his team have installed in her courtyard will bring some relief.

“My husband and I are saving up to buy a solar-operated fan too, so that we can bear 16-hour long electricity cuts that are routine in summer months,” she says. “I am praying summer [will be] bearable this year.”

In part one of this article: ‘My body feels like lead’: Heat is making pregnancy a nightmare in Karachi

This article originally appeared on Dialogue Earth and has been reproduced with permission