title: Effect of 21-day and 24-day oral contraceptive regimens containing gestodene (60 microg) and ethinyl estradiol (15 microg) on ovarian activity.
abstract: OBJECTIVE
  To compare ovulation inhibition and ovarian activity with 21-day and 24-day regimens of a low-dose combined oral contraceptive (COC) containing 60 microg of gestodene and 15 microg of ethinyl estradiol.
  
  
  METHODS
  Interventional observational study.
  
  
  METHODS
  Reproductive medicine unit.
  
  
  METHODS
  Fifty-eight healthy volunteers aged 18-35 years.
  
  
  METHODS
  Ovarian activity was monitored every other day with the use of ultrasound to measure the diameters of follicle-like structures and blood samples to measure serum concentrations of 17beta-E2 and progesterone. Subjects were observed for five cycles: pretreatment and posttreatment control cycles and three cycles in which the COC was administered for either 21 or 24 days of each cycle.
  
  
  METHODS
  Occurrence of ovulation and evidence of ovarian activity.
  
  
  RESULTS
  The study was completed by 27 (90%) of the 30 subjects who received the 24-day regimen and by 24 (79%) of the 28 subjects who received the 21-day regimen. Ovulation was inhibited in all cycles in the 24-day group and in 74 of 75 cycles in the 21-day group. Luteinized unruptured follicles were seen in no cycles with the 24-day regimen and in 6 (8%) of 75 cycles with the 21-day regimen. Mean ovarian follicular development and serum 17beta-E2 and progesterone levels were lower in the 24-day group.
  
  
  CONCLUSIONS
  The 24-day regimen is an innovative strategy for maintaining effective ovulation inhibition at ultra-low doses of contraceptive steroids.
authors.affiliation: Department of Obstetrics, Gynaecology and Reproductive Healthcare, University of Manchester, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Sullivan
authors.forename: H
authors.initials: H
authors.lastname: Furniss
authors.forename: J
authors.initials: J
authors.lastname: Spona
authors.forename: M
authors.initials: M
authors.lastname: Elstein
mesh_terms: D000293:Adolescent; D000328:Adult; D002582:Cervix Mucus / Q000187:drug effects; D003280:Contraceptives, Oral, Synthetic / Q000008:administration & dosage*; D004338:Drug Combinations; D004341:Drug Evaluation; D004958:Estradiol / Q000097:blood; D004997:Ethinyl Estradiol / Q000008:administration & dosage*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000187:drug effects; D009652:Norpregnenes / Q000008:administration & dosage*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000187:drug effects; D010060:Ovulation / Q000187:drug effects*; D045167:Progesterone Congeners / Q000008:administration & dosage*; D014463:Ultrasonography
chemical_list: D003280:Contraceptives, Oral, Synthetic; D004338:Drug Combinations; D009652:Norpregnenes; D045167:Progesterone Congeners; C033273:Gestodene; D004997:Ethinyl Estradiol; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone