Offspring preterm birth and birth size are related to long-term risk of maternal diabetes.

The aim of the study is to investigate the association between gestational age, birth size, and the long-term risk of maternal diabetes. We conducted a nation-wide prospective follow-up study of the cohort of all Danish women with a singleton delivery in 1982/1983 (index delivery) and no history of diabetes (n = 100,669). Registries were used to extract information on patients with a hospital or outpatient diagnosis of diabetes, subsequent deliveries, and death/emigration in the period from the index delivery until the end of 2006. The association between the maternal risk of diabetes and the index gestational age and index offspring birth size (birth weight adjusted for gestational age) was investigated by using Cox proportional hazards regression models stratified according to young (≤33 years) and old age (>33 years). During a median follow-up period of 24 years, 2,021 women (2.0 %) were diagnosed as having diabetes. The risk of maternal diabetes was positively associated with increasing index birth size and negatively associated with increasing duration of index gestation in both age strata. Among young women, the highest hazard ratios were found for the exposure category of large index offspring birth size (adjusted HR 9.0, 95 % CI 6.17-13.12) and a preterm delivery at 32-37 weeks (adjusted HR 2.22, 95 % CI 1.46-3.40). Offspring preterm birth and large size for gestational age at birth are associated with increased risk of maternal diabetes.