title: Do cycle disturbances explain the age-related decline of female fertility? Cycle characteristics of women aged over 40 years compared with a reference population of young women.
abstract: BACKGROUND
  The cause of declining fertility with age, in women who still have regular menstrual cycles, is not clear.
  
  
  METHODS
  Follicle development, endometrial growth and hormonal patterns were evaluated in cycles of older women (aged 41-46 years; n = 26) who previously were normally fertile, and these cycles were compared with a reference group of relatively young fertile women (aged 22-34 years; n = 35).
  
  
  RESULTS
  Clearly abnormal cycles were found in only two women in the older age group, and in one woman in the younger group. The main differences between the age groups were a shorter follicular phase and cycle length in the older group, in combination with higher FSH levels in the late luteal and early follicular phase. In contrast to published data which suggest an "accelerated" follicle development in older women, sonographical and hormonal evidence was found of an "advanced" follicle growth, with an earlier start already during the luteal phase of the preceding cycle, and an advanced selection and ovulation of the dominant follicle.
  
  
  CONCLUSIONS
  Such an earlier start of follicle growth in a possibly less favourable hormonal environment, as well as a limited oocyte pool, may contribute to a decreased follicle and oocyte quality, resulting in diminished fertility in ageing women.
authors.affiliation: Department of Reproductive Medicine, Division of Obstetrics, Neonatology and Gynecology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. p.vanzonneveld@azu.nl
authors.forename: P
authors.initials: P
authors.lastname: van Zonneveld
authors.forename: G J
authors.initials: GJ
authors.lastname: Scheffer
authors.forename: F J M
authors.initials: FJ
authors.lastname: Broekmans
authors.forename: M A
authors.initials: MA
authors.lastname: Blankenstein
authors.forename: F H
authors.initials: FH
authors.lastname: de Jong
authors.forename: C W N
authors.initials: CW
authors.lastname: Looman
authors.forename: J D F
authors.initials: JD
authors.lastname: Habbema
authors.forename: E R
authors.initials: ER
authors.lastname: te Velde
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase / Q000097:blood; D006801:Humans; D008183:Luteal Phase / Q000097:blood; D008597:Menstrual Cycle / Q000502:physiology*; D008875:Middle Aged; D006080:Ovarian Follicle / Q000502:physiology; D010053:Ovary / Q000000981:diagnostic imaging; D010060:Ovulation / Q000502:physiology; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D005640:Follicle Stimulating Hormone