Moderate exposure to cold and heat during early pregnancy may affect fetal development as early as the first trimester, according to a new study led by the Barcelona Institute for Global Health (ISGlobal), a center supported by the "la Caixa" Foundation. The findings, based on two Dutch birth cohorts and published in the International Journal of Epidemiology, suggest that early gestational development may be sensitive to ambient temperature, with potential implications for birth outcomes and long-term health as climate conditions continue to change.