Variable Variable NC (n=1676) AC (n=8057) P-value
Female age at oocyte retrieval (y) 31.19 ± 4.86 31.19 ± 4.86 30.46 ± 4.92 <0.001
Female age at embryo transfer (y) 31.66 ± 4.72 31.66 ± 4.72 30.89 ± 4.85 <0.001
Infertility duration (y) 3.43 ± 2.97 3.43 ± 2.97 3.47 ± 2.88 0.565
BMI (kg/m2) 21.80 ± 2.88 21.80 ± 2.88 22.23 ± 3.17 <0.001
<18.5 (n, %) 153 (9.93) 153 (9.93) 709 (9.30)
18.5-25 (n, %) 1196 (77.61) 1196 (77.61) 5544 (72.70)
>25 (n, %) 192 (12.46) 192 (12.46) 1373 (18.00)
AFC (n) 10.91 ± 5.15 10.91 ± 5.15 12.97 ± 6.07 <0.001
No. of oocyte retrieved (n) 11.98 ± 6.69 11.98 ± 6.69 13.78 ± 7.58 <0.001
Fertilization type (n, %) 0.948
   IVF 1148 (73.45) 1148 (73.45) 5681 (73.65)
   ICSI 370 (23.67) 370 (23.67) 1821 (23.61)
IVF+ICSI 45 (2.88) 45 (2.88) 211 (2.74)
Infertility type (n, %) 0.220
   Primary infertility 842 (54.50) 842 (54.50) 4036 (52.79)
Secondary infertility 703 (45.50) 703 (45.50) 3609 (47.21)
Protocol in the fresh cycle (n, %) 0.004
Agonist 1127 (72.48) 1127 (72.48) 5726 (74.43)
Antagonist 307 (19.74) 307 (19.74) 1537 (19.98)
Other 121 (7.78) 121 (7.78) 430 (5.59)
Previous fresh embryo transfer (n, %) 741(44.21) 741(44.21) 3858(47.88) 0.006
Clinical pregnancy in fresh cycles (n, %) 427(57.6) 427(57.6) 2134(55.3) 0.246
Single blastocyst transfer (n, %) 0.764
No 1343 (80.13) 1343 (80.13) 6482 (80.45)
Yes 333 (19.87) 333 (19.87) 1575 (19.55)
Endometrial thickness on the day of P administration(mm) 10.94 ± 1.93 10.94 ± 1.93 9.98 ± 1.55 <0.001
<7 21 (1.25) 21 (1.25) 137 (1.70)
≥7 1655 (98.75) 1655 (98.75) 7909 (98.30)
Triple-line endometrial pattern (n, %) 0.005
A 284 (16.96) 284 (16.96) 1130 (14.05)
B 1274 (76.06) 1274 (76.06) 6388 (79.41)
C 117 (6.99) 117 (6.99) 526 (6.54)
Type of embryo transferred (n, %) 0.121
Cleavage stage 752 (44.87) 752 (44.87) 3449 (42.81)
Blastocyst stage 924 (55.13) 924 (55.13) 4608 (57.19)
No. of transferred embryos (n, %) 0.219
1 461 (27.51) 461 (27.51) 2126 (26.39)
2 1188 (70.88) 1188 (70.88) 5835 (72.42)
3 27 (1.61) 27 (1.61) 96 (1.19)
No. of transferrable embryos (n) 6.42 ± 4.00 6.42 ± 4.00 7.26 ± 4.53 <0.001
No. of good quality embryos transferred (n, %) 0.001
0 660 (39.40) 660 (39.40) 2770 (34.38)
1 592 (35.34) 592 (35.34) 3051 (37.87)
2 423 (25.25) 423 (25.25) 2236 (27.73)