The purpose was to elucidate the association between parity and the incidence of diabetes using national register data.
The study population consisted of all Danish women with a singleton delivery in 1982/1983 (n = 100,669), who subsequently had 74,966 deliveries. The included women were followed up via registries until the end of 2006 for subsequent deliveries, diagnosis of diabetes and death/emigration.
A total of 2021 cases (2.0%) were diagnosed with diabetes in connection with hospitalization or outpatient treatment during follow-up. Analyses were adjusted for fetal weight and duration of gestation, both at index pregnancy. Cox regression analysis with parity as a time-varying exposure, stratified in two age groups, showed an association between parity and risk of a diagnosis of diabetes. In women 33 years of age, parity 2 was associated with a significantly lower risk of diabetes diagnosis compared with parity 1, whereas parity 4 + was associated with a significantly higher risk of diabetes diagnosis compared with parity 1.
The study shows that the risk of diabetes diagnosis increases with parity in young Danish women. This may support a causal association between diabetes and parity.