title: Parity and risk of diabetes in a Danish nationwide birth cohort.
abstract: OBJECTIVE
  The purpose was to elucidate the association between parity and the incidence of diabetes using national register data.
  
  
  METHODS
  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.
  
  
  RESULTS
  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, 3 and 4 + were associated with an increased risk of being diagnosed with diabetes compared with parity 1 [relative risks: 1.6 (95% confidence interval 1.1-2.3), 2.8 (1.8-4.3) and 2.5 (1.3-4.8), respectively]. Among 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Obstetrics and Gynaecology, Copenhagen University Hospital, Hvidovre, Denmark. kvnaver@gmail.com
authors.forename: K V
authors.initials: KV
authors.lastname: Naver
authors.forename: S
authors.initials: S
authors.lastname: Lundbye-Christensen
authors.forename: A
authors.initials: A
authors.lastname: Gorst-Rasmussen
authors.forename: L
authors.initials: L
authors.lastname: Nilas
authors.forename: N J
authors.initials: NJ
authors.lastname: Secher
authors.forename: S
authors.initials: S
authors.lastname: Rasmussen
authors.forename: P
authors.initials: P
authors.lastname: Ovesen
mesh_terms: D000328:Adult; D003718:Denmark / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010298:Parity; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012042:Registries / Q000706:statistics & numerical data; D012307:Risk Factors