Fertility in people with childhood-onset type 1 diabetes

To assess the number of live births in a population-based, retrospective cohort of women and men with childhood-onset type 1 diabetes, and matched controls.

The reproductive histories of people in a Finnish cohort of 2,307 women and 2,819 men with type 1 diabetes and two matched controls (for each case) were obtained from National Population Register data. All persons with diabetes were diagnosed with the disease in 1965-1979 at the age of 17 or under. A proportional hazards model was used to model the association between the rate of live births as a function of the age of an individual and the observed covariates (sex and age at onset of diabetes).

Both women and men with diabetes had a smaller number of live births than the controls; the HR of having a first child for diabetic women compared with controls was 0.66 (95% CI 0.62, 0.71) and for men was 0.77 (95% CI 0.72, 0.83). In women, a birth cohort effect was detected; in more recent birth cohorts, the difference between diabetic women and controls as regards having children was significantly smaller than in earlier cohorts. Later age at onset of diabetes was associated with a higher rate of having a first child among men (p = 0.04) and having a second live birth among women (p = 0.002).

Type 1 diabetes affects the number of live births in both women and men. The age at onset of diabetes is associated with the pattern of reproduction in both diabetic women and men.