The association between offspring birthweight and future risk of maternal diabetes: a population-based study

Aims — As an indicator of maternal cardio-metabolic health, newborn birthweight may be an important predictor of maternal type 2 diabetes mellitus (diabetes). We evaluated the relation between offspring birthweight and onset of maternal diabetes after pregnancy.

Methods — This retrospective cohort study used linked population-based health databases from Ontario, Canada. We included women aged 16-50 years without pre-pregnancy diabetes, and who had a live birth between 2006-2014. We used Cox proportional hazard regression to evaluate the association between age- and sex-standardized offspring birthweight percentile categories and incident maternal diabetes, while adjusting for maternal age, parity, year, ethnicity, gestational diabetes (GDM) and hypertensive disorders of pregnancy. Results were further stratified by the presence of GDM in the index pregnancy.

Results — Of 893,777 eligible participants, 14,329 (1.6%) women were diagnosed with diabetes over a median (IQR) of 4.4 (1.5-7.4) years of follow up. There was a continuous positive relation between newborn birthweight above the 75th percentile and maternal diabetes. Relative to a birthweight between the 50th and 74.9th percentile, women whose newborn had a birthweight between the 97th and 100th percentile had an adjusted hazards ratio (aHR) of diabetes of 2.30 (95% CI 2.16-2.46), including an aHR of 2.01 (95% CI 1.83-2.21) among those with GDM, and 2.59 (2.36-2.84) in those without GDM.

Conclusions — A higher offspring birthweight signals an increased risk of maternal diabetes, offering another potentially useful way to identify women especially predisposed to diabetes.