AbstractWe aimed to assess the association between exposure to sunshine during gestation and the risk of type 1 diabetes (T1D) in Danish children.The study population included 331,623 individuals born in Denmark from 1983 to 1988; 886 (0.26%) developed T1D by the age of 15 years. The values of sunshine hours were obtained from the Danish Meteorological Institute. Gestational exposure to sunshine was calculated by summing recorded monthly sunshine hours during the full 9 months prior to the month of birth. The linear variable then was split into two categories separated by the median value.Cox regression models showed that more sunshine during the third gestational trimester was associated with lower hazards (HR) of T1D at age 5–9 years in males: HR (95% CI): 0.60 (0.43–0.84), p=0.003. Our results should be considered in the context of evidence-based recommendations to the public about skin protection from the sun.