The central finding
DuoStim combines follicular- and luteal-phase ovarian stimulation in one menstrual cycle. A ten-year single-centre report describes the additional oocytes, euploid embryos and live births obtained after the second stimulation. It does not determine whether DuoStim is superior to two conventional stimulations performed sequentially.
What DuoStim is intended to do
The strategy uses two waves of follicular recruitment. After the first stimulation and oocyte retrieval, treatment resumes in the luteal phase and a second retrieval is performed before the next menstrual cycle. The aim is to accumulate oocytes quickly, not to improve the intrinsic quality of each oocyte.
DuoStim is therefore most relevant when time is clinically important or when a low expected yield makes oocyte accumulation a priority.
What the cohort reported
The study included 1,896 DuoStim cycles in 1,656 poor-prognosis, time-sensitive patients treated at one private centre between 2015 and 2024. Eligibility reflected age, low ovarian reserve or a previous poor response. The median time to cycle conclusion was 40 days, and median time to live birth was 145 days. The cumulative live-birth rate was 28.5% per concluded DuoStim cycle.
Adding the second stimulation increased the number of patients with at least one euploid blastocyst by 66% and those with at least one live birth by 125% compared with the result after the first stimulation alone.
Why added yield is not comparative effectiveness
A second retrieval creates another opportunity to obtain oocytes and embryos. Comparing the first stimulation with the sum of the first and second therefore demonstrates incremental yield, not the superiority of one treatment strategy over another.
The relevant comparison is DuoStim versus two conventional stimulations delivered over an equal time horizon, with similar patients and the same criteria for cancellation, embryo testing and transfer. The study did not randomize such strategies and did not include a parallel conventional two-cycle comparator.
Single-centre expertise, selection, changes in practice over ten years and extensive use of ICSI and PGT-A also limit generalizability.
Denominators and PGT-A
Success rates can be reported per started cycle, concluded cycle, patient, retrieval or transfer. These denominators answer different questions. The 28.5% figure applies to concluded DuoStim cycles in this cohort; it is not a personalized probability for every patient.
The probability of obtaining at least one euploid embryo also depends on the number of blastocysts available for biopsy and on the testing strategy. PGT-A does not turn an observational cohort into a comparative trial.
Potential benefit and treatment burden
The most plausible benefit is time consolidation. This can matter before gonadotoxic therapy, with very low ovarian reserve or when delaying another retrieval is undesirable. The trade-off is two periods of injections, monitoring and retrieval within a short interval, together with financial and emotional burden.
Patients should ask why time is critical, what oocyte target is realistic, whether and why PGT-A is planned, what happens after a poor first retrieval, what the total cost will be and how the strategy compares with two conventional cycles.
A balanced conclusion
DuoStim may be a sensible option for carefully selected patients when time matters. The cohort provides useful real-world information about trajectories and additional yield. It does not prove greater biological efficacy than two conventional stimulations. Shared decision-making should make that uncertainty explicit.
Source: Vaiarelli A et al. Frontiers in Endocrinology. 2026. https://doi.org/10.3389/fendo.2026.1854570
This educational information does not replace individual treatment planning.