In France and across the globe, the number of births has dropped significantly. According to the French National Institute for Statistics and Economic Studies (Insee), there were 24% fewer births in 2025 compared to 2010, which was the last peak in fertility. The conjunctural fertility indicator (ICF), which measures the average number of children a woman is expected to have during her lifetime, has fallen from 2 in 2014 to 1.56 in 2024—the lowest since the end of World War I. This decline is not unique to France; across Europe and other developed countries, the average fertility rate is now 1.4 children per woman. In France, younger people are increasingly expressing a desire for fewer children, with more individuals considering having no children or only one. Among those under 30, the average number of children people want has decreased by 0.6 over the past 20 years, from 2.5 to 1.9 for women and from 2.3 to 1.8 for men. Despite this, the French population is still growing slightly (+0.25%), and the natural balance—births minus deaths—remains positive, with a net increase of 17,000 people. In early 2024, President Emmanuel Macron called for a "demographic rearmament," positioning this issue as a key pillar of France's national strategy. A United Nations study highlights several factors contributing to the decline in fertility. Economic difficulties, such as job insecurity and housing challenges, are among the top concerns, with 39% of respondents citing these as a reason for having fewer children. Other factors include the difficulty of accessing childcare, the unequal division of household responsibilities, and health issues like chronic diseases or infertility. In France, nearly 15% of couples have trouble conceiving, and the average age of motherhood has decreased to 29 years. Environmental pollution and limited access to medically assisted procreation also play a role. Additionally, many people are choosing to have fewer children due to concerns about the future—social, political, and environmental. According to the National Institute for Demographic Studies (Ined), 35% of people aged 25 to 39 who are very worried about the future of coming generations are less likely to want to have a child compared to those who are less concerned. On average, they want 0.11 fewer children. Economists Paolo Melindi-Ghidi and Thomas Seegmuller from the Aix-Marseille School of Economics (AMSE) examined how pollution might influence fertility decisions. They found that the relationship between a country's fertility rate and its level of pollution is as strong as the traditional link between fertility and economic development. In the United States, for example, states with more carbon-intensive economies, like Texas, have higher fertility rates, while states like California, which produce less carbon, have lower fertility rates. This seems counterintuitive, as one might expect people in more polluted areas to have fewer children. However, the researchers found that environmental concerns are closely tied to the level of pollution in a region. In areas with less pollution, more people support stronger environmental regulations, while in highly carbon-intensive regions, people are more likely to see these regulations as harmful to the economy and employment. To incorporate environmental factors into their analysis, the researchers added an environmental index to the traditional equation that links fertility to quality of life. This index measures the ratio of green goods (products that are environmentally friendly) to polluting goods in an economy. The higher the production of green goods, the lower the carbon intensity and the higher the environmental index. This index reflects environmental quality as it influences household choices, much like the cost of living does. The researchers found that economies with lower carbon intensity are associated with stronger environmental concerns and better environmental quality. If improvements in environmental quality reduce the number of children people want, then fertility rates could decline further. According to Thomas Seegmuller, this suggests that people may have fewer children because they feel more confident about the environment improving. However, this connection between fertility and the environment raises a complex issue: the more people there are, the more pollution is generated, unless there is a fundamental change in how societies live and consume. Economic studies suggest that a decrease in population might not necessarily be a negative outcome, but the relationship between fertility and the environment remains a complicated equation.