Norethisterone stops implant-related prolonged bleeding
Oral norethisterone acetate was more effective than placebo for stopping prolonged bleeding in etonogestrel implant users, but bleeding often returned soon after stopping pills.
*Randomized, blinded, placebo-controlled trial; Level 1b (OCEBM).

Citation

Andrade MCRA, Yamaguti EMM, de Nadai MN, et al. Norethisterone for prolonged uterine bleeding associated with etonogestrel implant (IMPLANET): a randomized controlled trial. American Journal of Obstetrics & Gynecology. 2026;234(1):101–115. doi:10.1016/j.ajog.2025.08.029

Background

Prolonged bleeding is a common reason people stop the etonogestrel contraceptive implant. Extra progestogen pills are often used, but evidence has been limited.

Patients

Adults aged 18–40 in Brazil using an etonogestrel implant ≥40 days, with ≥7 consecutive days of bleeding and no other identified cause.

Intervention

Norethisterone acetate 10 mg by mouth daily until 2 bleeding-free days or up to 30 days; repeatable for new episodes.

Control

Matching placebo using the same instructions.

Outcome

Bleeding stopped within 7 pills (primary); additional bleeding outcomes and safety.

Follow-up Period

Up to 210 days.

Results

Outcome Norethisterone acetate Placebo Absolute difference
Bleeding stopped within 7 pills (primary) 86.7% (39/45) 48.9% (22/45) +37.8%; NNT 3
Bleeding stopped within 14 pills 91.1% (41/45) 64.4% (29/45) +26.7%; NNT 4
Treatment failure (bleeding continued after 30 days of pills) 2.2% (1/45) 17.8% (8/45) -15.6%; NNT 7
Days of pills until bleeding stopped (median) 3 days 5 days 2 days faster
Bleeding-free days in first 30 days (median) 21 days 13 days +8 days
Time to bleeding return after stopping pills (median) 5 days 10.5 days 5.5 days sooner
NNT = number needed to treat.
Primary outcome used a modified intention-to-treat approach; several time-based outcomes used a per-protocol approach.

Limitations

Brazil-only sample; many dropouts after day 30; placebo tablets lacked drug imprint; longer-term bleeding outcomes were harder to interpret.

Funding

Organon Investigator-Initiated Studies Program; industry funding may bias results.

Clinical Application

For bothersome prolonged bleeding with the etonogestrel implant, consider short-course norethisterone acetate to stop bleeding, while counseling that recurrence is common within days.