The effect of combined oral contraception on testosterone levels in healthy women: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of experimental studies.
PubMed 24082040 · doi:10.1093/humupd/dmt038
What was done
A systematic review and random-effects meta-analysis evaluated the effects of combined oral contraceptives (COCs) on total testosterone (T), free T, and sex hormone-binding globulin (SHBG) in healthy women. Searches across MEDLINE, EMBASE, and Cochrane Central covered studies up to July 2012. Subgroup analyses evaluated the impact of estrogen dose (20–25 µg vs. 30–35 µg ethinylestradiol [EE]), progestin type, and assay methods.
What was found
Across 42 experimental studies (1,495 healthy women aged 18–40), COC use significantly decreased total T (mean difference [MD] -0.49 nmol/L, 95% CI -0.55 to -0.42; P < 0.001) and free T (relative change 0.39, 95% CI 0.35 to 0.43; P < 0.001, representing a mean decrease of 61%). SHBG levels increased significantly (MD 99.08 nmol/L, 95% CI 86.43 to 111.73; P < 0.001). Total and free T reductions did not differ by EE dose or progestin type, but SHBG increases were significantly smaller with 20–25 µg EE and second-generation progestins.
Why it matters
This review quantifies the substantial suppression of circulating androgens caused by COCs, showing that free testosterone falls by more than half primarily driven by large increases in SHBG across all common formulations.
Limits
Half of the included studies (21 of 42) were non-comparative experimental designs rather than randomized controlled trials. The meta-analysis was restricted to biochemical measurements in healthy women aged 18–40, and the abstract notes that clinical implications (such as impacts on sexual function or mood) were not evaluated.
Cited by
- supports Combined oral contraceptives increase SHBG levels in women, suppressing total testosterone by 50% to 60% and free testosterone by 70% to 80%.
- supports Oral contraceptives artificially suppress testosterone levels in women.