Not applicable.

12 May 2011.

STUDY QUESTION Do cumulative live birth rates (CLBRs) over multiple IVF/ICSI cycles confirm the low prognosis in women stratified according to the POSEIDON criteria? SUMMARY ANSWER The CLBR of low-prognosis women is ~56% over 18 months of IVF/ICSI treatment and varies between the POSEIDON groups, which is primarily attributable to the impact of female age. WHAT IS KNOWN ALREADY The POSEIDON group recently proposed a new stratification for low-prognosis women in IVF/ICSI treatment, with the aim to define more homogenous populations for clinical trials and stimulate a patient-tailored therapeutic approach. These new criteria combine qualitative and quantitative parameters to create four groups of low-prognosis women with supposedly similar biologic characteristics. STUDY DESIGN, SIZE, DURATION This study analyzed the data of a Dutch multicenter observational cohort study including 551 low-prognosis women, aged <44 years, who initiated IVF/ICSI treatment between 2011 and 2014 and were treated with a fixed FSH dose of 150 IU/day in the first treatment cycle. PARTICIPANTS/MATERIALS, SETTING, METHODS Low-prognosis women were categorized into one of the POSEIDON groups based on their age (younger or older than 35 years), anti-Müllerian hormone (AMH) level (above or below 0.96 ng/ml), and the ovarian response (poor or suboptimal) in their first cycle of standard stimulation. The primary outcome was the CLBR over multiple complete IVF/ICSI cycles, including all subsequent fresh and frozen-thawed embryo transfers, within 18 months of treatment. Cumulative incidence curves were obtained using an optimistic and a conservative analytic approach. MAIN RESULTS AND THE ROLE OF CHANCE The CLBR of the low-prognosis women was on average ~56% over 18 months of IVF/ICSI treatment. Younger unexpected poor ( n = 38) and suboptimal ( n = 179) responders had a CLBR of ~65% and ~68%, respectively, and younger expected poor responders ( n = 65) had a CLBR of ~59%. The CLBR of older unexpected poor ( n = 41) and suboptimal responders ( n = 102) was ~42% and ~54%, respectively, and of older expected poor responders ( n = 126) ~39%. For comparison, the CLBR of younger ( n = 164) and older ( n = 78) normal responders with an adequate ovarian reserve was ~72% and ~58% over 18 months of treatment, respectively. No large differences were observed in the number of fresh treatment cycles between the POSEIDON groups, with an average of two fresh cycles per woman within 18 months of follow-up. LIMITATIONS, REASONS FOR CAUTION Small numbers in some (sub)groups reduced the precision of the estimates. However, our findings provide the f...