Introduction: Controlled ovarian stimulation (COS) overcomes the selection of a dominant follicle and enables recruitment of a cohort of multiple follicles. Often we face a situation when only one egg is retrieved, either following natural cycle (NC) IVF or after COS with poor ovarian response to treatment. Aim: The aim of this study was to determine the prognosis for couples that following an IVF treatment cycle had only a single oocyte retrieved. The prognosis was determined by stratifying the study population into different groups according to: age (40), treatment protocol (COS vs NC), fertilization method (IVF vs ICSI) and the influence of the ovarian reserve. Materials & Methods: In a retrospective cohort study, we identified all the women treated by IVF in our center between the years 1996-2011, in whom a single oocyte was retrieved, either following NC modified NC (MNC) or COS cycles. Overall, 243 cycles, performed in 166 patients, are included. The primary outcome measure in this study is the live birth rate (LBR) according to the different sub-groups mentioned earlier. The secondary outcome measures are the probability of reaching embryo transfer and the probability of achieving pregnancy. Results: The overall fertilization rate was 69.13% (168/243 cycles) and embryo transfer was performed in 63.37% of cycles (154/243 cycles). There were 21 pregnancies (8.64% per cycle and 13.63% per embryo transfer), but only 7 live births (2.88% per cycle and 4.54% per embryo transfer). The probability of live birth in the age group ≤ 40 was significantly higher (5.3% vs. 0%) than in the group >40 (p=0.016). The probability of achieving pregnancy was not significantly different between the treatment protocols. The probability of live birth was 2.1% (4 women) in the COS group, 2.4% (1 case) in the MNC group, and 13.3% (2 cases) in the NC group (p=0.044). The probability achieving fertilization (77.7% vs 59.8%; P = 0.009), reaching embryo transfer (70.4% vs 54.2%; p=0.011) and live birth (5.2% vs 0%; p=0.019) was significantly higher with the use of ICSI than with standard IVF. Conclusion: The results of our study demonstrate the extremely poor prognosis in IVF cycles in which only one oocyte is retrieved. A live birth rate of 2.9% per cycle and 4.5% per embryo transfer are substantially low compared to results normally achieved with IVF. Our results may aid in counseling patients undergoing IVF under similar circumstances.
