As extreme heat days rise due to climate change, pregnant individuals face higher health risks. Heat-related conditions like heatstroke, dehydration, and respiratory issues are becoming more common. However, pregnant people are especially vulnerable to these dangers.
A new analysis by Climate Central, published on May 14, highlights the growing threat. Between 2020 and 2024, the number of pregnancy heat-risk days doubled in 222 countries. These are days when temperatures exceed 95% of historical records for that location. The biggest increases were seen in the Caribbean, Central and South America, and sub-Saharan Africa—regions with limited access to healthcare.
Pregnancy makes heat regulation harder. Shruthi Mahalingaiah, associate professor at Harvard T.H. Chan School of Public Health, explains that pregnancy alters the body’s ability to cool itself. The body is already supporting a fetus, making it harder to maintain a healthy internal temperature. This raises the risk of heat-related complications.
Heat exposure increases the risk of pregnancy complications. Anna Bonell, assistant professor at the London School of Hygiene & Tropical Medicine, notes that extreme heat can lead to conditions like pre-eclampsia and gestational diabetes. It can also affect fetal development, increasing the risk of birth defects such as neural tube defects like spina bifida.
Additionally, extreme heat is linked to higher rates of preterm and early-term births. A 2024 study in JAMA Network Open found that prolonged heat waves raised these risks. Preterm births can lead to higher infant mortality, frequent hospitalizations, and long-term health issues.
High temperatures also affect reproductive healthcare tools. Contraceptives and pregnancy tests can lose effectiveness if exposed to extreme heat. Since 2011, an estimated 11.5 million women across 26 countries have faced disrupted access to contraception due to climate-related displacement, according to MSI Reproductive Choices.
Marginalized communities are hit hardest. Howie Wu, assistant professor at Columbia University, emphasizes that lower-income populations with limited healthcare access suffer the most. Lack of air conditioning, poor housing, and proximity to pollution sources increase vulnerability to heat-related health problems.
Other climate stressors also affect pregnancy outcomes. Air pollution has been linked to high blood pressure during pregnancy, low birth weight, preterm birth, and impaired fetal brain and lung development, according to the World Health Organization. Severe storms, such as hurricanes, have been shown to trigger early births due to stress, contamination, and disrupted health services.
Climate change also threatens healthcare infrastructure. A December 2023 report by XDI revealed that climate change has raised the risk of hospital damage by 41%. Such damage can disrupt prenatal care. For example, Hurricane Sandy severely impacted healthcare services in New York City, limiting access to prenatal care, notes Wu.
Experts call for more research. Mahalingaiah stresses the need to better understand how climate change affects pregnancies and fetal development. “It’s very important to think about both upstream and downstream impacts in the reproductive life cycle,” she says. “We have much more work to do.”
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