Double Stimulation Protocol May Accelerate Embryo Retrieval for Older IVF Patients
DuoStim lets women with poor ovarian reserve collect more eggs in one cycle, potentially cutting time to a successful pregnancy.
Summary
As more women pursue IVF at advanced ages, getting enough viable embryos for genetic testing often requires multiple stimulation cycles spread over months. This clinical trial tested whether a double stimulation protocol — called DuoStim — could compress two retrieval rounds into a single menstrual cycle. Researchers at IVI Madrid enrolled women of advanced age with poor ovarian response, comparing DuoStim against two standard consecutive stimulation cycles. The primary question was whether the rate of chromosomally normal (euploid) embryos was equivalent between approaches. Secondary measures included total oocytes collected, mature oocyte count, number of embryos biopsied, and the MitoScore — a mitochondrial DNA marker linked to embryo viability. If DuoStim proves non-inferior, it could meaningfully shorten the path to pregnancy for a growing population of fertility patients.
Detailed Summary
Advanced maternal age is one of the most significant challenges in modern reproductive medicine. As women delay childbearing, ovarian reserve declines and chromosomal abnormalities in embryos rise sharply. Preimplantation genetic testing (PGT) can identify viable embryos before transfer, but poor responders often need multiple stimulation cycles to accumulate enough embryos — a process that can take many months and carries emotional and financial costs.
This randomized controlled trial from IVI Madrid investigated whether the DuoStim protocol — which involves two sequential ovarian stimulations within a single menstrual cycle, one in the follicular phase and one in the luteal phase — could deliver comparable embryological outcomes to two conventional cycles while significantly compressing the timeline. The study enrolled women of advanced reproductive age with poor ovarian response, assigning them to either DuoStim or two standard controlled ovarian hyperstimulation cycles run consecutively.
The primary endpoint was the rate of euploid embryos per cycle — a measure of both embryo quantity and chromosomal quality assessed by PGT. Secondary endpoints included total and mature oocyte yield, blastocyst biopsy numbers, and the MitoScore index, which quantifies mitochondrial DNA content in embryos and may serve as an additional marker of implantation potential beyond conventional euploidy testing.
The researchers hypothesized that euploid embryo rates would be similar across both protocols, suggesting DuoStim could be a time-efficient alternative without compromising genetic quality. If confirmed, this has meaningful implications for older patients for whom time is a critical biological variable.
The trial is listed as completed, though full published results are not yet available from the abstract alone. Caveats include the single-center design, which may limit generalizability, and the specialized patient population. The inclusion of MitoScore adds novelty but its clinical predictive value remains debated in the field.
Key Findings
- DuoStim compresses two retrieval rounds into one menstrual cycle, potentially halving time to embryo accumulation.
- Primary endpoint compares euploid embryo rates between DuoStim and two consecutive conventional stimulation cycles.
- MitoScore (mitochondrial DNA index) used as a secondary quality marker alongside standard PGT euploidy results.
- Target population is advanced-age poor responders — among the most challenging and growing groups in IVF.
- Researchers hypothesize DuoStim yields similar euploid rates, supporting it as a time-saving non-inferior strategy.
Methodology
This is a unicentric, prospective, randomized, non-blind, parallel-group controlled phase IV clinical trial conducted at IVI Madrid. Women of advanced reproductive age with poor ovarian response were randomized to DuoStim (follicular plus luteal phase stimulation in one cycle) versus two consecutive conventional controlled ovarian hyperstimulation cycles. PGT was used to assess embryo euploidy as the primary outcome.
Study Limitations
This summary is based on the abstract only; full results, statistical outcomes, and patient numbers are not available. The single-center design at IVI Madrid may limit generalizability to other clinical settings and populations. The clinical utility of MitoScore as an embryo selection tool remains a subject of ongoing debate in the reproductive medicine literature.
Enjoyed this summary?
Get the latest longevity research delivered to your inbox every week.