In the present study, 812 patients with POR diagnosis were investigated which in overall 517 of them had embryo transfer in the last treatment cycle (63.6%) and total clinical pregnancy rate 19.3% (100 cases) and live birth rates 16.1% (86 cases) were found. When the patients were grouped on the basis of the POSEIDON classification, the highest live birth rate was observed in the POSEIDON group III. On the other hand, according to the Bologna criteria, 41 patients were not included in any group, and in the analysis of cycle outcome, the live birth rate in the Bologna group II was more than other groups. It is noteworthy that the POSEIDON classification groups were significant predictive factor for live birth in the multivariable regression analysis. According to univariate regression analysis the women age ≥ 35 years was associated with 60% decreased likelihood of live birth; it can be interpreted that in POSEIDON group classification the age cut-off point (35 years) was significant factor in predicting live birth. It is suggested that POSEIDON group classification to be more comprehensive and practical than Bologna criteria for diagnosing and categorizing POR patients.
In the similar way, La Marca and colleagues (2015) compared the live birth rates in 210 POR patients in different Bologna groups and reported same poor prognosis for all groups. Elsewhere Busnelli et al. (2015), in a retrospective study, evaluated 362 patients with POR diagnosis in different group according to Bologna criteria and reported the live birth rate (6%), which were similarly poor among different groups of Bologna criteria. In their study, positive predictive factors of live birth were previous deliveries and previous chemotherapy, but age, serum AMH, serum FSH and AFC were not significantly associated with live birth. Of course, this study suggested using the Bologna criteria for designing future studies in this area. Similarly, Bozdag and colleagues (2017) in a retrospective study compared live birth rates in 821 patients in different Bologna groups and found no statistically significant difference in the rate of live births. In contrast to previous studies, Li and colleagues (2017) retrospectively evaluated 132 women undergoing the second IVF treatment cycle, who diagnosed as POR by the Bologna criteria. In this study, women aged ≥ 40 years and/or having history of endometriosis or ovarian surgery were taken as Bologna 1; those having 3 or less oocytes retrieved in the previous IVF cycle stimulated with a standard protocol were considered as Bologna 2, while those with AFC ≤ 6 were classified as Bologna 3.They concluded that the POR patients fulfilling different combinations of the Bologna criteria hadn’t similar IVF outcomes. The best ovarian response and live-birth rate were observed in those with Bologna 1 + 2 with normal AFC, and the worse in those with Bologna 1 + 2 + 3.
In a recent study, Eftekhar et al. (2018) in a retrospective study evaluate live birth rates in 245 POR patients in different group on the basis of POSEIDON group classification and concluded the live birth rates in groups I and II were higher than those of in groups III and IV. In thier study the ovarian stimulation protocol (microdose agonist flare-up) was used in all study groups and the authors mentioned that in contrast to previous studies, which reported women age as the most important predictor of ART success, in their study the ovarian reserve factor (AMH And AFC) were the main predictive factors. In present study, we found no relationship between live birth rates and different ovarian stimulation protocols in our study population by univariate regression analysis; this issue is challenging subject in the management of POR patients. Youssef et al. in a multicenter randomized trial concluded that a mild ovarian stimulation strategy in women with poor ovarian reserve undergoing IVF leads to similar ongoing pregnancy rates as a conventional ovarian stimulation strategy [17]. In similar way, Pilehvari and colleagues have suggested that minimal stimulation protocol with lower gonadotropin used could be considered as a patient-friendly and cost-effective substitute for PORs [18]. In present study number and quality of transferred embryos were the important related variables with probability of live birth in POR patients, so we suggest pooling method for collecting more oocytes and embryos by consecutive minimal stimulation protocols to improve the success rate in POR patients.
In line with our study results, Haung and colleagues (2018) evaluated 1957 patient with a diagnosis of diminished ovarian reserve. In their study, the patient's age, the number and quality of the transfer embryos are the most predictive factors of live birth in this population. In addition, Xu et al. (2018) in a recent study evaluate the cumulative live birth (CLBR) rates in more than 3,000 patients with poor ovarian response: a 15-year survey of final in vitro fertilization outcome. They reported that the CLBR decreased from 22% for women ≤ 30 years to 18.3% for women aged 31–34 years, 17.2% for 35–37 years, 13.5% for 38–40 years, 10.5% for 41–43 years, and 4.4% among women > 43 years in the conservative analysis; therefore, an optimistic estimate in these patients is a challenging subject for clinicians.
The strengths of the study are the high sample size of POR patients and also presented the cycle outcomes according to two main diagnostic criteria in this field. As limitation of present study, we could not apply the same protocol COH for all POR patients according to our institute policy; individual COH protocols considering the age and ovarian reserve and the previous patient's treatment cycles. Therefore, the multivariable logistic regression analysis was used to determine the main predictive factors for live birth rate in POR patients.
On the basis of present results, the high prevalence of the POR patients according to Bologna criteria and POSEIDON group classification were in group III and IV and the most of clinical trial studies should designed to improve cycle outcomes in these patients. In addition, in present study, was found the number and quality of transferred embryos were the most important prognostic factor for live birth in POR patients; therefore we suggest to consider COH protocols with a freezing embryos strategy, and the collection of more good quality embryos to improve the probability of a live birth.