title: Fecundability among women with type 1 and type 2 diabetes in the Norwegian Mother and Child Cohort Study.
abstract: OBJECTIVE
  We assessed the effects of type 1 diabetes and type 2 diabetes on fecundability (as manifest by increased time-to-pregnancy [TTP]) in a large cohort of pregnant women.
  
  
  METHODS
  This study is based on the Norwegian Mother and Child Cohort Study. Members of this large cohort were enrolled early in pregnancy and asked about TTP and other factors. Among the 58,004 women included in the analysis, we identified 221 cases of type 1 diabetes and 88 cases of type 2 diabetes using the Medical Birth Registry of Norway. A logistic analogue of the proportional probability model, a Cox-like discrete-time model, was used to compute fecundability odds ratios (FORs) and 95% CI for type 1 diabetes and type 2 diabetes, adjusted for maternal age and prepregnancy BMI.
  
  
  RESULTS
  Compared with non-diabetic women, the adjusted FOR for women with type 1 diabetes was 0.76 (95% CI 0.64-0.89) and the adjusted FOR for women with type 2 diabetes was 0.64 (95% CI 0.48-0.84). These FORs did not change substantively and remained statistically significant after excluding women with irregular menstrual cycles and accounting for cycle length.
  
  
  CONCLUSIONS
  The results from the present study provide evidence of substantially decreased fecundability for women with type 1 and type 2 diabetes, even among those with a normal menstrual cycle.
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, P.O. Box 12233, Mail Drop A3-05, Durham, NC 27709, USA. whitworthkw@niehs.nih.gov
authors.forename: K W
authors.initials: KW
authors.lastname: Whitworth
authors.forename: D D
authors.initials: DD
authors.lastname: Baird
authors.forename: L C
authors.initials: LC
authors.lastname: Stene
authors.forename: R
authors.initials: R
authors.lastname: Skjaerven
authors.forename: M P
authors.initials: MP
authors.lastname: Longnecker
mesh_terms: D000328:Adult; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005260:Female; D005298:Fertility; D006801:Humans; D009664:Norway; D011247:Pregnancy; D011795:Surveys and Questionnaires