Estrogen or anti-estrogen for Bologna poor responders?

The current study aims to compare cycle outcomes of two ovarian stimulation protocols in poor responders according to the Bologna criteria; luteal estrogen priming (LE) or letrozole (LZ) co-treatment in antagonist protocol. Following retrospective chart review of a single center, 162 cycles were found eligible for the comparison of two ovarian stimulation protocols. After interpreting data, significantly higher serum estradiol levels, longer duration of cycle, higher number of fertilized oocytes and good quality embryos were detected in patients who received LE. Despite any statistical significance, higher clinical pregnancy rate (CPR) and ongoing pregnancy rate (OPR) per embryo transfer (ET) were detected with LE protocol compared with LZ (12.3% versus 18.2% and 9.6% versus 12.7%, respectively). Younger patients (<40 years) revealed higher CPR and OPR per started cycle compared with older patients (≥40 years) where only OPR was statistically significant. Multivariable analysis demonstrated that basal antral follicle count, peak serum estradiol levels and number of fertilized oocytes were independent variables significantly associated with clinical pregnancies (p < 0.05). In the current analysis, LE or LZ protocols revealed comparable but quite low pregnancy rates in poor responders according to the Bologna criteria. Younger patients were more likely to achieve pregnancy compared to older patients with both protocols.