The April 2024 heatwave was linked to an estimated 8,830 additional preterm births in India, according to an analysis by international non-profit research group Zero Carbon Analytics. The finding turns an extreme-weather event into a public-health measure: heat is not only an outdoor discomfort or a threat to workers, but also a stressor affecting pregnancy and newborn survival.
The analysis found that human-driven climate change made the heatwave at least 45 times more likely. Across India, Bangladesh and the Philippines, the heatwave was linked to 10,600 additional preterm births. The overall heatwave, including the effect of heat occurring during a typical April, was associated with around 16,150 more preterm births than would have occurred during a typical April in recent decades.
That distinction matters. The estimate attributed specifically to climate change is smaller than the total additional burden associated with the heatwave, but it identifies the part of the risk that is connected to a changing climate. As temperatures rise, heat exposure becomes a concern not only for emergency response systems but also for routine maternal and neonatal care.
Preterm birth means that a baby is born before 37 weeks of gestation. It is the leading cause of newborn deaths worldwide, while premature babies also face a higher risk of long-term health and developmental problems. The figures therefore connect climate resilience with health-system capacity: protecting people from heat is also about reducing avoidable pressure on maternity services and improving the chances of healthy births.
The national estimate also shows that the risk is not evenly distributed. Bihar, Uttar Pradesh, West Bengal and Jharkhand accounted for around two-thirds of the additional preterm births in India that were linked to the heatwave, according to the analysis. The concentration points to the importance of looking beyond national averages when designing heat-health measures. A countrywide temperature alert may be useful, but the burden of exposure and the capacity to respond can differ substantially between states and communities.
India’s estimated increase in preterm births linked to the heatwave was 3.6%, compared with 11.9% in Bangladesh and 10% in the Philippines. The comparison does not make India’s burden less significant. India’s larger population means that a lower percentage increase can still translate into a much higher absolute number of additional births. It also shows why climate-health planning needs to consider both rates and population scale.
The available evidence does not establish that every additional preterm birth in the estimate occurred because of one individual heat exposure or one clinical episode. It presents a population-level association between the April heatwave, climate change and preterm births. That makes the result a planning signal rather than a case-by-case diagnosis. For public agencies, however, population-level evidence is precisely what is needed to decide where surveillance, communication and medical preparedness should be strengthened.
Doctors cited in the report describe the physiological pathway in straightforward terms. Arun Nayak, who heads the gynaecology department at BMC-run Sion Hospital, said extreme climatic conditions can affect pregnant women. He said extreme heat could cause dehydration or stress, with the release of hormones that could predispose women to preterm labour.
The explanation also brings the climate issue into the everyday operation of cities. Pregnancy does not occur in an abstract climate zone. Women may be exposed to heat in homes, on public transport, at workplaces, in informal settlements or while travelling to hospitals. The supplied evidence does not quantify the contribution of each setting, but it establishes that heat-related stress can intersect with pregnancy and that the risk has been reported by doctors and community organisations.
The timing of pregnancy may matter as well. Western studies cited in the report have shown that risks are particularly high during the third trimester. The source material does not provide the details of those studies, so it cannot establish how the risk varies across Indian regions or different types of heat exposure. It does, however, identify a group that could require more targeted communication and clinical attention during heatwaves.
Bhagwan Keshbhat of the NGO Waatavaran told the Times of India that pregnancy-related problems increase during heatwaves. Women also reported such difficulties during community discussions organised by the NGO in rural Maharashtra. These accounts add a ground-level dimension to the national estimate, while also showing the limits of relying only on hospital data. Symptoms, difficulties in accessing care and pregnancy-related distress may appear in communities before they are consistently captured in administrative records.
The policy challenge is therefore larger than issuing a heat alert. A heat-health response that focuses only on temperature thresholds may miss the needs of pregnant women, particularly those who have limited access to cooling, water, transport or timely medical care. The source material does not list a specific government programme or implementation protocol for this risk. What it does show is that existing heat events are already producing measurable health consequences, and that these consequences need to be visible within urban and public-health planning.
This is especially relevant to municipal systems. Urban administrations influence several conditions that shape heat exposure, including public water access, neighbourhood services, transport operations, public health messaging and the functioning of local hospitals. The report does not attribute the additional preterm births to any particular city or municipal failure. It would therefore be inaccurate to assign responsibility beyond the evidence. But the finding does establish that heat preparedness has implications for institutions that manage both the urban environment and frontline services.
The projected future burden makes the planning question more urgent. The analysis estimates that by mid-century, India could see more than 15,000 additional preterm births during a typical April due to heat, exceeding the estimated burden during April 2024. Uttar Pradesh is projected to face the highest burden, followed by Bihar and Rajasthan. These are projections, not observed outcomes, and the supplied material does not specify the assumptions behind them. Their significance lies in the direction of the risk: a heat-health burden observed during one event could become larger during an ordinary month as temperatures rise.
The regional context is already serious. South Asia had the world’s highest preterm birth rate in 2020, at 13.2%, according to the figures cited in the analysis. Bangladesh had the highest national rate among the three countries at 16.2%, followed by India at 13%. The Philippines recorded a rate of 7.7%. These numbers describe the underlying prevalence of preterm birth, while the heatwave estimate describes an additional burden associated with a specific event. They should not be treated as interchangeable measures, but together they show why climate exposure can intensify an existing health challenge.
The numbers also reveal a governance problem: the people most affected by heat may not be the people most visible in climate planning. Heat action is often understood through deaths, hospital admissions or outdoor labour risks. The evidence in this analysis expands that frame to include pregnancy outcomes, newborn survival and longer-term developmental health. Such outcomes can remain dispersed across households and facilities, making them harder to identify during an emergency even though their consequences extend well beyond the heatwave itself.
For cities, the issue is not limited to whether average temperatures are rising. It is whether public systems can identify vulnerable residents, communicate risk in time and maintain access to care during extreme conditions. The supplied evidence does not measure the effectiveness of existing heat action plans, nor does it compare preparedness across Indian cities or states. It does show that climate-related heat exposure is already associated with an outcome that affects families, hospitals and the future health of children.
The April 2024 heatwave therefore provides two connected signals. The first is immediate: climate change was linked to thousands of additional preterm births in India, with the largest burden concentrated in four states. The second is structural: as heat becomes more likely, maternal and neonatal health will increasingly depend on whether climate planning is connected to healthcare delivery and community-level realities.
What remains uncertain in the supplied evidence is how the burden varies by city, occupation, housing condition, trimester, access to cooling and quality of healthcare, as well as which interventions reduce the risk most effectively. Those gaps do not weaken the central finding. They identify the next layer of evidence needed if heat-health planning is to move from broad warnings to protection for pregnant women and newborns.
