Table 1 The baseline characteristics and laboratory data of the Day 3 transfer (women with clinical pregnancy) and control groups

Number of patients

275

110

Female Age (years)

29.71 ± 2.74

30.02 ± 2.71

0.322

Male Age (years)

31.31 ± 3.58

31.34 ± 3.50

0.953

Female BMI (kg/m²)

21.55 ± 2.51

21.43 ± 2.38

0.647

Infertility duration (years)

3.34 ± 2.14

3.28 ± 2.13

0.776

bFSH

7.72 ± 2.39

7.41 ± 2.06

0.229

Gn dosage (IU/L)

2350.32 ± 650.17

2351.36 ± 615.55

0.988

Oocytes retrieved (n)

Fertilization model (%)

11.05 ± 3.94

11.04 ± 4.15

0.974

0.899

IVF

226 (82.2)

91 (82.7)

ICSI

49 (17. 2)

19 (17.3)

Endometrial thickness on ET day (cm)

11.76 ± 6.28

11.04 ± 2.11

0.240

No. of embryos transferred, n (%)

0.016*

1

21/529 (4.0)

17/203 (8.4)

2

508/529 (96.0)

186/203 (91.6)

MII oocytes rate (%)

88.48% (2689/3039)

87.81% (1066/1214)

0.537

2PN oocytes rate (%)

69.32% (2054/2963)

66.05% (782/1184)

0.041*

Cleavage rate of 2PN oocytes (%)

98.20% (2017/2054)

98.08% (767/782)

0.836

Available embryo rate at Day 3 (%)

82.44% (1663/2017)

78.49% (602/767)

0.016*

High-quality embryo rate at Day 3 (%)

27.12% (547/2107)

27.77% (213/767)

0.331

Blastocyst formation rate (%)

66.71% (1118/1676)

66.51% (419/630)

0.928

High-quality embryo rate for transplantation

41.97% (222/529)

40.39% (82/203)

0.699

Available blastocyst formation rate (%)

48.45% (812/1676)

48.73% (307/630)

0.904

Day 5 available blastocyst formation rate (%)

33.29% (558/1676)

35.08% (221/630)

0.419