title: Oral contraceptive use and bone density change in adolescent and young adult women: a prospective study of age, hormone dose, and discontinuation.
abstract: BACKGROUND
  Oral contraceptive (OC) use is common, but bone changes associated with use of contemporary OC remain unclear.
  
  
  OBJECTIVE
  The objective of the study was to compare bone mineral density (BMD) change in adolescent and young adult OC users and discontinuers of two estrogen doses, relative to nonusers.
  
  
  METHODS
  This was a prospective cohort study, Group Health Cooperative.
  
  
  METHODS
  Participants included 606 women aged 14-30 yr (50% adolescents aged 14-18 yr): 389 OC users [62% 30-35 μg ethinyl estradiol (EE)] and 217 age-similar nonusers; there were 172 OC discontinuers. The 24-month retention was 78%.
  
  
  METHODS
  The main outcome measure was BMD measured at 6-month intervals for 24-36 months.
  
  
  RESULTS
  After 24 months, adolescents using 30-35 μg EE OCs, but not those using lower-dose OCs, had significantly smaller adjusted mean percentage BMD gains than nonusers at the spine [group means (95% confidence interval for between group differences) 1.32 vs. 2.26% (-1.89, -0.13%)] and whole body [1.45 vs. 2.03% (-1.29%, -0.13%)]. Adolescents who discontinued 30-35 μg EE OC showed significantly smaller gains than nonusers at the spine after 12 months [0.51 vs. 1.72% (-2.38%, -0.30%)]. Young adult OC users did not differ from nonusers. However, OC discontinuers of both doses differed significantly from nonusers at the spine 12 months after discontinuation [-1.32% < 30 μg EE, -0.92% 30-35 μg EE vs. +0.27% nonusers (-2.48, -0.54, and -1.94%, -0.55%, respectively)]. Results were similar for mean absolute BMD change (grams per square centimeter).
  
  
  CONCLUSIONS
  Both OC use and discontinuation were associated with BMD losses/smaller gains relative to nonusers (differences < 2% after 12-24 months for all skeletal sites). The clinical significance of these results regarding future fracture risk is unknown. Study of longer-term trends after discontinuation is needed.
authors.affiliation: Group Health Research Institute, Group Health Cooperative, 1730 Minor Avenue, 16th Floor, Seattle, Washington 98101, USA. scholes.d@ghc.org
authors.forename: Delia
authors.initials: D
authors.lastname: Scholes
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Hubbard
authors.forename: Laura E
authors.initials: LE
authors.lastname: Ichikawa
authors.forename: Andrea Z
authors.initials: AZ
authors.lastname: LaCroix
authors.forename: Leslie
authors.initials: L
authors.lastname: Spangler
authors.forename: Jeannette M
authors.initials: JM
authors.lastname: Beasley
authors.forename: Susan
authors.initials: S
authors.lastname: Reed
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ott
mesh_terms: D000293:Adolescent; D000328:Adult; D015519:Bone Density / Q000187:drug effects*; D003278:Contraceptives, Oral, Hormonal / Q000494:pharmacology* / Q000627:therapeutic use; D004997:Ethinyl Estradiol / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D011446:Prospective Studies; D011859:Radiography; D013131:Spine / Q000000981:diagnostic imaging / Q000187:drug effects*
chemical_list: D003278:Contraceptives, Oral, Hormonal; D004997:Ethinyl Estradiol