title: A proposed classification system for menstrual cycles in the menopause transition based on changes in serum hormone profiles.
abstract: OBJECTIVE
  To characterize menstrual cycles in women in late reproductive age and the menopause transition, based on changes in serum hormone levels.
  
  
  METHODS
  Serum levels of estradiol, progesterone, follicle-stimulating hormone (FSH), luteinizing hormone, inhibin A, inhibin B, and antimüllerian hormone, as previously reported as mean data grouped according to the Stages of Reproductive Aging Workshop proposals, were analyzed in 55 women aged 45 to 55 and compared with those in 21 women aged 21 to 35.
  
  
  RESULTS
  The ovulatory cycles in the older women were divided into three types. Type 1 cycles (n = 14, 33%) were those with hormone concentrations similar to the women aged 21 to 35 except for 20-fold lower antimüllerian hormone levels. Type 2 cycles (n = 24; 53%) had increased FSH, decreased inhibin B, and increased FSH-to-inhibin B ratios but normal estradiol and progesterone levels. Type 3 cycles had the same characteristics as type 2 cycles (n = 5; 12%) in addition to lower luteal phase progesterone and increased luteinizing hormone.
  
  
  CONCLUSIONS
  The changes in hormone levels indicated in cycle types 1 to 3 closely reflect the changes in ovarian-pituitary activity as menopause approaches and are likely to be directly attributable to a decrease in ovarian follicle reserve. The findings suggest that FSH-to-inhibin B ratios and antimüllerian hormone are distinct early indicators of the menopause transition and are likely to be useful biomarkers of impending menopause. Furthermore, this classification may provide an improved basis for the study of reproductive endocrine disorders associated with the menopause transition.
authors.affiliation: Prince Henry's Institute, Monash Medical Centre, Clayton, Victoria, Australia. david.robertson@princehenrys.org
authors.forename: David M
authors.initials: DM
authors.lastname: Robertson
authors.forename: Georgina E
authors.initials: GE
authors.lastname: Hale
authors.forename: Ian S
authors.initials: IS
authors.lastname: Fraser
authors.forename: Claude L
authors.initials: CL
authors.lastname: Hughes
authors.forename: Henry G
authors.initials: HG
authors.lastname: Burger
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004958:Estradiol / Q000097:blood; D005640:Follicle Stimulating Hormone / Q000097:blood*; D005498:Follicular Phase / Q000097:blood* / Q000502:physiology*; D006801:Humans; D007265:Inhibins / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D008593:Menopause / Q000097:blood / Q000502:physiology*; D008875:Middle Aged; D011374:Progesterone / Q000097:blood
chemical_list: D011374:Progesterone; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone