Overview of combined hormonal contraception

Combined hormonal contraception is available as combined oral contraceptives (COCs) or the contraceptive vaginal ring, which contain both:

an estrogen—estetrol, estradiol (or its prodrug estradiol valerate), ethinylestradiol or mestranol
a progestogen—cyproterone, desogestrel, dienogest, drospirenone, etonogestrel, gestodene, levonorgestrel, nomegestrol or norethisterone.

Combined hormonal contraceptives primarily work by suppressing ovulation; they also cause thickening of cervical mucus.

COCs and vaginal rings are equivalent in effectiveness, contraindications and precautions, drug interactions and adverse effects. The vaginal ring can be a useful option if a nonoral method of combined hormonal contraception is preferred, or if unscheduled bleeding occurs with the COC. See Comparison of combined oral contraceptives and the contraceptive vaginal ring for a comparison of the COC and the vaginal ring.

Table 1. Comparison of combined oral contraceptives and the contraceptive vaginal ring
Characteristic	Combined oral contraceptive	Contraceptive vaginal ring
daily action required	yes; compliance errors possible at any time	no, but compliance errors can occur with insertion of a new ring (risk of breakthrough ovulation is highest at the end of the hormone-free interval)
effectiveness	93% with typical use 99.5% with perfect use	93% with typical use 99.5% with perfect use
absorption affected by vomiting, severe diarrhoea or malabsorption	yes	no
breakthrough bleeding	more frequent than with vaginal ring	less frequent than with COC (superior cycle control)
device-related symptoms and problems	none	may cause increased physiological vaginal discharge or discomfort may be accidentally expelled self-insertion may be unacceptable
cost	some formulations available on PBS	not available on PBS
Note: COC = combined oral contraceptive; PBS = Pharmaceutical Benefits Scheme Modified with permission from: Contraception: an Australian clinical practice handbook. 4th ed. Ashfield, New South Wales: Family Planning New South Wales, Family Planning Victoria, and True Relationships and Reproductive Health; 2016.