Efficacy, safety and acceptability of once-monthly oral contraceptives containing quinestrol and quingestanol, quinestrol and levonorgestrel or quinestrol and norgestrel: a systematic review
In brief
Case series of monthly quinestrol pills found 3.6% pregnancies; nearly half discontinued
In case series of one monthly quinestrol combination, 3.6% of participants became pregnant and pooled discontinuation was 47.9%, with estimates varying widely. The review included 5,355 people, but only one randomized trial, which found no significant pregnancy difference between two formulations; most evidence was low or very low certainty, leaving safety and effectiveness uncertain.
- Journal
- BMJ sexual & reproductive health (Q1)
- Published
- 23 September 2026
- Study design
- Systematic review / meta-analysis of RCTs
- Evidence level
- Level 1, High (CEBM 1a)
- Authors
- Yuanyuan Yao, Hui Liu, Bingyi Wang, Meihua Wu, Huayu Zhang, Haodong Li, et al.
- PMID
- 42778304
- DOI
- 10.1136/bmjsrh-2026-203330
Why clinicians should know about it
- Picked for Obstetrics and Gynecology (paper of the day, 27 September 2026): Quinestrol monthly oral contraceptives systematic review
Abstract
OBJECTIVE: To evaluate the efficacy, safety and acceptability of quinestrol combined with quingestanol (Quin-QUIN), quinestrol combined with levonorgestrel (Quin-LNG) and quinestrol combined with norgestrel (Quin-NG) as contraceptives. METHODS: PubMed, Web of Science Core Collection, Embase, CENTRAL, CINAHL, CNKI, Wanfang, SinoMed and selected supplementary sources were systematically searched to identify randomised controlled trials (RCTs) and non-randomised studies of interventions related to Quin-QUIN, Quin-LNG and Quin-NG. Two investigators independently performed data extraction and risk-of-bias assessment. A random-effects model was used for the meta-analysis and the certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. RESULTS: Twelve studies (1 RCT and 11 case series) involving 5355 participants were included. Most studies were published in the 1970s. The only included RCT showed no significant difference in the risk of pregnancy (risk ratio (RR)=0.70, 95% confidence interval (CI) 0.31 to 1.55 for Quin-LNG compared with Quin-NG). Quin-LNG was associated with a lower risk of discontinuation and fewer side effects than Quin-NG. Proportion meta-analyses of the case series, all evaluating Quin-QUIN, found a pooled proportion of pregnancy of 3.6% (95% CI 2.5% to 5.0%) and a pooled discontinuation rate of 47.9% (95% CI 17.4% to 79.4%). Nausea, vomiting, dizziness and headache were the most common side effects. The certainty of evidence for most outcomes was low or very low. CONCLUSIONS: Available evidence is limited; the risk-benefit profile of quinestrol-based once-monthly oral contraceptives remains uncertain. Their clinical use should be cautious, and high-quality studies are needed to clarify their safety and efficacy.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.