Rima Dhillon-Smith: Progesterone Capsules Boost ART Success Rates
Rima Dhillon-Smith, Consultant Gynaecologist and subspecialist in Reproductive Medicine at NHS, shared a post on LinkedIn about a paper published in Human Reproduction:
“I’m really pleased to share that our study ‘A comparison of progesterone via vaginal oil capsules versus pessaries for luteal phase support in assisted reproduction treatment: a multicentre cohort study of 42 291 cycles’ has been published in Human Reproduction.
Key findings:
- We found that using vaginal oil capsules of progesterone for luteal phase support in ART (both fresh IVF/ICSI and HRT-FET) was associated with higher live birth rates compared to pessary forms: 34.3% vs 27.8% in fresh cycles, aRR 1.11 (95% CI 1.04-1.19); 36.7% vs 32.9%, aRR 1.09 (95% CI 1.04-1.14) in HRT-FET cycles after adjustment for confounders.
- In HRT-FET cycles, the miscarriage rate was significantly lower in the oil-capsule group compared to pessaries (adjusted risk ratio 0.87; 95% CI 0.82–0.93), though for fresh cycles the adjusted difference did not reach statistical significance.
- This study is retrospective and observational, so while we adjusted for many confounders, we cannot account for residual confounding.
What’s next:
We hope this work lays the foundation for a well-powered RCT comparing these progesterone modalities directly, with a focus on live birth and miscarriage rates. In clinical practice, the findings encourage fertility clinics and patients to discuss the route/formulation of progesterone support as part of shared decision-making.
Thank you to all our co-authors at Care Fertility (Birmingham, Manchester, Nottingham, Northampton), the University of Birmingham/NIHR Birmingham Biomedical Research Centre, and the University of Oxford for their collaboration, and to all the Care Fertility patients whose data made this research possible.”
Title: A comparison of progesterone via vaginal oil capsules versus pessaries for luteal phase support in assisted reproduction treatment: a multicentre cohort study of 42 291 cycles
Authors: R. K. Dhillon-Smith, M. Khairy, T. Bamford, V. Sephton, A. Richardson, A. H. Balen, A. Coomarasamy
Read the full article.

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