Send to

Choose Destination
See comment in PubMed Commons below
Contraception. 2012 Dec;86(6):710-5. doi: 10.1016/j.contraception.2012.05.004. Epub 2012 Jun 6.

Comparison of cervical mucus of 24/4 vs. 21/7 combined oral contraceptives.

Author information

Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.



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.


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.


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.


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.

[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Support Center