Comparison of cervical mucus of 24/4 vs. 21/7 combined oral contraceptives.
BACKGROUND
Few studies have examined the action of combined oral contraceptives (COCs) on cervical mucus. We hypothesized that midcycle cervical mucus of women taking COCs is of poor quality when compared to their own midcycle mucus prior to initiating COCs. We sought to compare the effect upon quality and sperm penetration of the cervical mucus on the last hormone-free day with a 24/4 regimen to a 21/7 regimen.


METHODS
This is an open-label, investigator-blinded, randomized, controlled, crossover equivalency study. All subjects received, in random order, 2 months of a 21/7 regimen and 2 months of a 24/4 regimen, each containing 20 mcg ethinyl estradiol and 1 mg norethindrone acetate. Analysis of cervical mucus quality (CMQ) and sperm penetration took place midcycle and on the last day of the hormone-free interval during the second month of each COC treatment.


RESULTS
From April 2010 to November 2011, 18 subjects completed all study visits. Mean midcycle CMQ was poor (mean CMQ=1) and did not differ between 24/4 and 21/7 regimens (p=.92). On the last day of the pill-free interval, the quality and sperm penetration were poor with both regimens.


CONCLUSIONS
This study indicates that thickening of cervical mucus is a major mechanism of contraceptive action of COCs and that both 21/7 and 24/4 regimens result in poor quality and impenetrable mucus on the last day of the pill-free interval.
Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. rachelst@usc.edu
Rachel
R
Steward
Alexander
A
Melamed
Anna
A
Granat
Daniel R
DR
Mishell
D000328:Adult; D002582:Cervix Mucus / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D002584:Cervix Uteri / Q000187:drug effects* / Q000378:metabolism; D055598:Chemical Phenomena / Q000187:drug effects; D003277:Contraceptives, Oral, Combined / Q000008:administration & dosage / Q000494:pharmacology*; D018592:Cross-Over Studies; D015925:Cryopreservation; D004334:Drug Administration Schedule; D004997:Ethinyl Estradiol / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D008597:Menstrual Cycle; D009640:Norethindrone / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D000077563:Norethindrone Acetate; D010352:Patient Dropouts; D012662:Semen Preservation; D016037:Single-Blind Method; D013083:Sperm Transport; D014783:Viscosity / Q000187:drug effects; D055815:Young Adult
D003277:Contraceptives, Oral, Combined; D004997:Ethinyl Estradiol; D000077563:Norethindrone Acetate; D009640:Norethindrone