Abstract. Pregnancy is a period of heightened susceptibility to external insults. In October 2024, an unprecedented torrential rain (DANA) struck South-East Spain. Concentrated in just a few hours and specific areas, it triggered severe flooding that caused 238 casualties and extensive property damage –the most devastating natural disaster in Europe so far in the 21st century. Using a Difference-in-Differences framework and administrative microdata on pre- and post-disaster births, in this study we analyse whether pregnant mothers who were exposed to the floods were more likely than those unexposed to deliver babies with poorer health outcomes. We also analyse dose-response patterns and test whether mothers in more exposed areas experienced heightened risks. Focusing on prematurity as an indicator of perinatal health that captures key social and physiological mechanisms at work, particularly stress, we find that babies exposed to the floods in utero at the final stages of gestation experienced significantly worse outcomes. These results provide new evidence of the intergenerational consequences of maternal stress triggered by acute natural disasters.