title: Oral contraceptive use in relation to age at menopause in the DOM cohort.
abstract: BACKGROUND
  We investigated the hypothesis that long-term use of oral contraceptives (OCs), in particular high-dose OCs, could postpone age at menopause.
  
  
  METHODS
  Data was used from 8701 women who participated in a breast cancer screening programme in Utrecht (DOM-3 cohort), and who did not use hormone replacement therapy (HRT) or OCs in the 4 years prior to their last menses. Data on OC-use, menopausal status, age at menopause, year of birth, parity, smoking behaviour, socio-economic status, body mass index and age at menarche was available. Use of high-dose OCs has been defined in this study as OC-use before 1972. The data was analysed by means of linear regression and Cox's proportional hazards analysis. Women still menstruating, women with surgical menopause and women lost to follow-up were censored at their last known date of menstruation. Endpoint was the natural menopause (n = 4589).
  
  
  RESULTS
  The use of high-dose OCs advanced the onset of menopause by approximately 1.2 months for every year of OC-use compared with no OC-use. High-dose OC-use for > or = 3 years, adjusted for confounding variables, increased the risk of earlier menopause compared with no OC-use (adjusted hazard ratio 1.12; 95% CI 1.03--1.21). The use of lower dose OCs did not increase the risk of earlier menopause (adjusted hazard ratio 1.00; 95% CI 0.91--1.09).
  
  
  CONCLUSIONS
  These results are inconsistent with the hypothesis that long-term use of OCs could postpone the onset of menopause by inhibiting follicle depletion. Possible explanations are discussed.
authors.affiliation: International Health Foundation, Utrecht, 3526 KS, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: de Vries
authors.forename: I
authors.initials: I
authors.lastname: den Tonkelaar
authors.forename: P A
authors.initials: PA
authors.lastname: van Noord
authors.forename: Y T
authors.initials: YT
authors.lastname: van der Schouw
authors.forename: E R
authors.initials: ER
authors.lastname: te Velde
authors.forename: P H
authors.initials: PH
authors.lastname: Peeters
mesh_terms: D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D003276:Contraceptives, Oral / Q000008:administration & dosage / Q000009:adverse effects*; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D016014:Linear Models; D008572:Menarche; D008593:Menopause; D008875:Middle Aged; D009426:Netherlands; D010298:Parity; D016016:Proportional Hazards Models; D012907:Smoking; D012959:Socioeconomic Factors
chemical_list: D003276:Contraceptives, Oral