Objective: Clinical prognosis appears to be varied in females with poor ovarian response (POR), and poor responders defined by the Bologna criteria might not be sufficiently homogeneous. The aim of this study was to determine the major predictor of reproductive outcomes in extremely low oocyte retrieval cycles.
Materials and methods: A cohort of fresh in vitro fertilization/intracytoplasmic sperm injection cycles (n = 858) was analyzed from January 2001 to September 2014. Females from whom zero, one, two, or three oocytes were retrieved following ovarian stimulation were examined. Univariate analyses were performed to determine the association of pregnancy rate with potential confounding variables. Multiple logistic regression analysis was subsequently performed to identify factors that affected the occurrence of pregnancy.
Results: The clinical pregnancy rate was higher in women aged < 40 years, long protocol, and high embryo score in univariate analysis. After adjusting for confounding factors in multivariate analysis, the maternal age [odds ratio (OR) = 0.91], primary or secondary infertility (OR = 1.99), number of matured oocytes retrieved (OR = 0.64), and score of embryos transferred (OR = 1.39) were significantly associated with the clinical pregnancy rate per cycle and per transfer. In the age subgroup analysis, POR females aged < 35 years significantly demonstrated the highest number of matured oocytes, embryo scores, and clinical pregnancy rates compared with POR females aged 35-40 years and ≥ 40 years.
Conclusion: This study highlights the predictive value of maternal age and embryo quality on the probability of pregnancy in females with extremely low oocyte retrieval cycles. Young females with few eggs collected can still achieve acceptable pregnancy probability as long as they have good-quality embryos. Future randomized control trials for POR using the Bologna criteria should first stratify patients into different age groups.
Keywords: Bologna criteria; age; embryo quality; poor ovarian response; stratification.
Copyright © 2017. Published by Elsevier B.V.