title: Growth rates of ovarian follicles during natural menstrual cycles, oral contraception cycles, and ovarian stimulation cycles.
abstract: OBJECTIVE
  To compare growth rates of ovarian follicles during natural menstrual cycles, oral contraception (OC) cycles, and ovarian stimulation cycles using standardized techniques.
  
  
  METHODS
  Prospective, comparative, observational, longitudinal study.
  
  
  METHODS
  Healthy volunteers in research trials and infertility patients undergoing treatment at an academic institution.
  
  
  METHODS
  Women were evaluated during natural cycles (n = 50), OC cycles (n = 71), and ovarian stimulation cycles (n = 131).
  
  
  METHODS
  Serial transvaginal ultrasonography was performed to measure follicle diameter. Day-to-day growth and regression profiles of individual follicles were determined. Mean growth rates were calculated for ovulatory follicles. Mean growth and regression rates were calculated for anovulatory follicles.
  
  
  METHODS
  Follicle growth rate (in millimeters per day).
  
  
  RESULTS
  Mean follicular growth rate was greater during ovarian stimulation cycles (1.69 +/- 0.03 mm/day) compared to natural (1.42 +/- 0.05 mm/day) and OC cycles (1.36 +/- 0.08 mm/day). The interval from dominant follicle selection to ovulation was shorter during stimulation cycles (5.08 +/- 0.07 days) compared to natural cycles (7.16 +/- 0.23 days).
  
  
  CONCLUSIONS
  Follicles grew faster during ovarian stimulation therapy compared to natural cycles or OC cycles. Greater follicular growth rates in stimulation cycles were associated with shorter intervals from selection to ovulation. The biologic effects of increased follicular growth rates and shorter intervals to ovulation on oocyte competence in women undergoing assisted reproduction remain to be determined.
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. angela.baerwald@usask.ca
authors.forename: Angela R
authors.initials: AR
authors.lastname: Baerwald
authors.forename: Randy A
authors.initials: RA
authors.lastname: Walker
authors.forename: Roger A
authors.initials: RA
authors.lastname: Pierson
mesh_terms: D000293:Adolescent; D000328:Adult; D003276:Contraceptives, Oral / Q000627:therapeutic use*; D005260:Female; D005300:Fertility Agents, Female / Q000627:therapeutic use*; D006801:Humans; D008137:Longitudinal Studies; D008597:Menstrual Cycle / Q000187:drug effects*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000502:physiology; D010060:Ovulation / Q000187:drug effects*; D010062:Ovulation Induction; D011446:Prospective Studies; D013997:Time Factors; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D003276:Contraceptives, Oral; D005300:Fertility Agents, Female