A low-dose combined pill cut menstrual blood loss ~44%; ferritin unchanged in iron-replete women but rose in heavy bleeders / low-iron women
Protocol
Prospective within-subject study, no control group described: 20 healthy, young women took a low-dose combined oral contraceptive (ethinyl estradiol 30 micrograms + desogestrel 0.15 mg) (from the abstract).
Menstrual blood loss (MBL) measured before starting and after 3 and 6 months of use.
Blood hemoglobin, hematocrit, erythrocyte indices and serum ferritin before and after 6 months; duration of menstruation and dysmenorrhea also recorded.
Key Findings
Low-dose combined OCP (30 µg EE + 0.15 mg desogestrel), n=20: menstrual blood loss fell 60.2 → 36.5 (3 mo) → 33.7 mL (6 mo) (~44%, P<0.001), concentrated in the first two days.
In this iron-replete cohort, serum ferritin was largely unchanged (44.2 → 39.7 µg/L).
Benefit concentrated in heavy bleeders: all 5 with baseline MBL >80 mL dropped below 80; both women with depleted stores (ferritin <10) increased ferritin on OCP.
Practical Application
OCP can be a legitimate iron-preservation lever specifically for athletes with heavy menstrual bleeding or recurrent iron deficiency — but a physician conversation, not a coaching prescription.
Don't expect the pill to raise ferritin in an athlete with normal periods and normal stores — small effect there; address iron via diet/screening.
If a female endurance athlete has both low ferritin and heavy periods, flag the pattern and refer for work-up (the two may be linked).
Limitations
Small (n=20), non-athlete, older (1992) formulation; measured MBL is a strength but athletes' iron losses also come from sweat/GI/foot-strike haemolysis; ferritin is an acute-phase reactant.
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How this entry was checked and changed
Content correction 2026-09-27
2026-09-28: added Protocol from the abstract (Europe PMC, DOI 10.1016/0010-7824(92)90095-b, PMID 1486771).