The effect of temperature on fertility: A province-level analysis of monthly total fertility rates in Italy in 2003 – 2022

Climate change-induced temperature increases and extreme weather events are impacting human health and wellbeing. Warmer temperatures are reported to affect both reproductive health and behaviors, possibly reducing birth rates. In a low fertility context, the potential negative impact that climate change might have on fertility is consequential. This study focuses on Italy, a low-fertility country disproportionately affected by climate change, with sharp regional disparities in both climate zones and economic development. Matching monthly birth registration data for the period 2003 to 2022 with E-OBS meteorological data, we analyze the relationship between heat exposure and total fertility rates in 107 Italian provinces (corresponding to the NUTS-3 classification). Results show that exposure to extremely hot days, which are defined as days with a mean temperature above 25°C, has a relatively immediate impact on conception probabilities as it reduces the total fertility rate nine months later. While this reduction is observed across both cold and hot climate zones, it appears to be larger for warmer provinces. The effect of temperature on fertility also varies with the per capita gross domestic product, where fertility rates in the richest provinces appear to be more sensitive to warming temperatures. The interaction between climate zones and GDP per capita revealed that hot above-average GDP provinces are the most affected by hot temperatures.