Reproductive health in women with childhood-onset type 1 diabetes in Finland

The aim of this study was to explore the development of reproductive health issues in women with childhood-onset type 1 diabetes (T1D) in Finland in recent decades, based on a large population-based cohort.
The study cohort consists of 2327 women and two individually matched control persons without diabetes for each person in the cohort. The cohort is part of the DERI (Diabetes Epidemiology Research International) cohort that was established at the beginning of the 1980s and it consists of all persons who were diagnosed with T1D at the age of seventeen or under in 1965–1979. The control persons are age-, sex- and birth place-matched persons without diabetes. Three of the studies are register-based cohort studies that compare women with and without diabetes in regard to four topics: family size, rates of terminations of pregnancy and sterilisation, and parity-related mortality. Studies I and IV also include men, both from the DERI cohort (n = 2819) and from the control group. The fourth study was a questionnaire study on menopausal age and factors affecting it, involving part of the study cohort. The survey results regarding age at menopause of T1D patients were compared with general population data.
The study women had fewer children than the controls without diabetes: the average number of children was lower in women with diabetes (1.1 [95% CI 1.03, 1.15]) than in women without diabetes (1.83 [95% CI 1.77, 1.87]), but in younger birth cohorts a significant trend was seen towards decreased differences between women with and without diabetes. There were significantly more terminations of pregnancy among women with diabetes (standardised incidence ratio [SIR] 1.67 [95% CI 1.51−1.86] compared with control women) and the indications for termination were different: maternal medical indications comprised 23.6% of terminations in the diabetes group and 0.3% in the women without diabetes. Sterilisations were more common (SIR 1.69 [95% CI 1.56−1.83] in the diabetes group and 22.9% them were carried out for maternal medical indications, the corresponding figure among the control women being 0.3%. The difference between women with and without type 1 diabetes regarding the frequency of sterilisation vanished around the year 2000.
Age at menopause was associated with the grade of complications of diabetes: the age-related occurrence of menopause was higher in women with severe microvascular complications, i.e., proliferative retinopathy or end-stage renal disease. The mean age at menopause was not lower than in the general population.
Mortality was lower in persons with children than in childless persons in our study, independent of sex and diabetes status, but the relationship between parity and mortality was different in men and women: in women with diabetes, having even one child was associated with lower mortality from diabetes compared with childless women, whereas in men, the difference was seen only in men with two children or more.
The studies indicate that differences in reproductive issues between women with and without childhood-onset T1D have decreased over time. Compared with women without diabetes, parity has been lower and the frequencies of terminations of pregnancy and sterilisations have been higher in women with T1D than in the general population. There are differences in parity-related mortality between women and men with T1D; the underlying reasons and mechanisms are not clear. If pregnancy has a protective effect in women with T1D, this could partly be explained by the fact that women with diabetes learn to maintain good metabolic control during pregnancy and that they are also motivated to keep up this good control after giving birth.
A high quality of life is a central aim of good diabetes care. Future studies should focus on factors affecting the fecundity and fertility of women with diabetes and whether an improvement in fertility also improves prognosis and quality of life.