Premature Luteinization Affect IVF Outcome in Controlled Ovarian Stimulation (COS) Cycles Using Flexible Antagonist Protocol

To investigate the relationship between serum progesterone (P4) levels on the hCG day and the IVF outcomes in the women undergoing COS for IVF/ICSI-ET using flexible antagonist protocol. The prospective study included a total 148 cycles of 148 IVF and/or ICSI-ET patients using flexible antagonist protocol from May, 2012 to June, 2012. The serum P4 levels were checked on the day of hCG administration. We take the cut-off value for premature luteinization as 0.97ng/mL which was the 75 percentile value of P4 level on hCG day. IVF outcomes such as No. of retrieved oocytes, maturation rate, fertilization rate, implantation rate, clinical pregnancy rate (CPR), miscarriage rate (MR) were compared according to P4 level. The correlation factors with P4 level were analysed with regression analysis and the cut-off value for each correlation factor was taken 75 percentile value. The incidence of premature luteinization was 26% (39/148). There was no difference in the mean age (33.9 ± 2.7 vs. 33.6 ± 2.7). The serum E2 level (4263±2366 pg/ml vs. 2270±1421 pg/ml, p<0.001), No. of retrieved oocytes (16.9±6.9 vs. 10.2±6.3, p<0.01) was significantly higher in low P4 group (P4≤0.97) and CPR (39.4 % vs. 20.5 %, p=0.033) was significantly higher in low P4 than high P4 group (P4>0.97). The serum P4 level showed significant positive correlation with serum E2 level and No. of retrieved oocytes. When P4 level was combined with No. of oocytes retrieved, the CPR (37.5 % vs. 15.05 %, p=0.049) and IR (17.3 % vs. 6.7 %, p=0.025) was significantly higher in low P4 (P4≤0.97) and No. of oocytes (No.≤16) group than those of high P4 (>0.97) and No. of oocytes (No.>16) group. Premature luteinization, elevated serum P4 level on the day of hCG, is associated with lower CPR although No. of retrieved oocytes is higher. Measuring serum P4 values at the time of HCG is necessary in order to adjust the strategy for embryo transfer. The larger scaled prospective study will be required.