Pregnancy and clinical outcomes
Table 1 presents the effects of different post-thawed culture periods on pregnancy and clinical outcomes. The results indicated that the post-thawed culture period had significant effects on pregnancy and clinical outcomes. In total age group, IR, CPR, MPR and LBR of L group were observed to be higher than that of S group (P /CI = 0.002/1.034-1.162, 0.027/1.011-1.194, 0.028/1.014-1.255 and 0.001/1.054-1.245 respectively), while EPR was significant high in short culture group (P /CI = 0.029/1.043-1.983) and AR was no significant difference between the two groups (P /CI = 0.172/0.962-1.260). In the < 35 year groups, IR, CPR and LBR were significant high in the L group compared with these in the S group (P /CI = 0.001/1.061-1.233, 0.004/1.056-1.332, 0.000/1.118-1.396 respectively), while AR and EPR were observed to be higher in the S group than these in the L group (P /CI = 0.036/1.015-1.472, 0.002/1.272-2.864 respectively). Moreover, MPR was high of L group than that of S group (P /CI = 0.071/0.990-1.280). In the 35-39 age group, IR, CPR, MPR, EPR and AR were similar between groups L and S, while LBR was observed to be higher in the L group than these in the S group (P /CI = 0.039/1.010-1.387). In the > 39 age group, there was no significant difference on IR, CPR, MPR, AR, EPR and LBR between S and L groups. Table 1 also displays the effect of female age on pregnancy and clinical outcomes. The results indicated that IR, CPR, MPR and LBR decreased significantly and AR increased significantly (P values were all less than 0.001) with age in the S and L groups, while EPR had not significant difference with age.
Table 2 shows the effect of blastomere growth number after long culture period of thawed D3 embryo on pregnancy and clinical outcomes. The results indicated that blastomere growth number had a significant effect on IR, CPR and LBR in all age groups (P values were all less than 0.001), and the faster the embryo developed, the better outcome was found. MPR significantly increased with the increase of blastomere growth number in < 35, 35-39 and total age groups (P =0.000, 0.001 and 0.000 respectively), while MPR was similar in > 39 age group (P = 0.235). AR was similar in < 35 and > 39 age groups (P = 0.353 and 0.948) and the rates of ≥ 2 blastomeres groups significantly decreased in 35-39 and total age groups (P = 0.028 and 0.050). Moreover, no significant differences were found in EPR among the four age groups. The IR, CPR and LBR of same blastomere growth number groups decreased significantly and AR increased significantly with age (P values were all less than 0.001).
A logistic regression model for predicting live birth is given in Table 3. Variables that were statistically significant in Table S1, or those that were deemed to be clinically significant, were included in order to build the model. This model indicated that the most significant predictors for live birth were female age, type of infertility and culture period (D3/D4). This model shows that the most significant predictors for live birth were female age, secondary infertility and long post-thawed culture period (P /CI = 0.00/0.89-0.91, 0.00/1.06-1.28 and 0.00/1.11-1.32 respectively).