Heat linked to fewer births in France and Italy

New studies show that high temperatures are directly linked to a decline in birth rates in France and Italy. Each day with an average temperature of 25°C or higher is associated with about 360 fewer births in France and 192 fewer in Italy, with the drop appearing nine to ten months after the heat exposure.

Heat affects reproductive health and behavior

The findings suggest that heat can harm the reproductive health of both men and women, potentially reducing the frequency of pregnancies. It may also influence sexual behavior, contributing to fewer conceptions during hot months.

Similar trends seen across other countries

Similar studies in the United States, South Korea, Spain, and other European nations have also found a link between heat and lower birth rates. However, previous research in the U.S. and Hungary showed that some missing births were later "made up," implying that couples might delay conception. This pattern is not observed in the French and Italian studies, suggesting a possible permanent loss of births.

Italy's low fertility rate and aging population

Italy was one of the first countries to fall below the threshold of 1.30 children per woman in the 1990s, a level known as "extremely low fertility." This has led to a rapidly aging population. France, while maintaining a higher fertility rate for longer, has seen a 24% decline in births from 2010 to 2025, now well below the level needed to sustain its population.

Europe's rising temperatures and heatwaves

Europe is warming faster than most other regions, with the Mediterranean particularly vulnerable. In Italy, average annual temperatures have risen nearly 2°C over the past 60 years, faster than the global average. This summer was the hottest in France since record-keeping began in 1900, with prolonged and severe heatwaves affecting the region.

Limitations and future uncertainties

While the studies indicate a real but relatively weak link between heat and lower birth rates, they do not conclusively prove causation. They rely on historical data and population-level trends rather than controlled experiments. As climate change accelerates, the relationship between heat and births could change, though current evidence suggests that other factors like family norms and financial pressures are still the main drivers of declining fertility.