Table 2 The baseline characteristics and laboratory data of the Day 5 transfer (women with clinical pregnancy) and control groups

Number of patients

81

46

Female Age (years)

29.33 ± 2.69

29.93 ± 2.71

0.230

Male Age (years)

30.86 ± 3.23

31.93 ± 4.25

0.113

Female BMI (kg/m²)

21.65 ± 2.63

21.55 ± 3.04

0.857

Infertility duration (years)

3.50 ± 1.96

3.33 ± 2.55

0.676

bFSH

7.53 ± 2.77

8.15 ± 4.04

0.305

Gn dosage (IU/L)

2251.24 ± 545.51

2281.79 ± 699.25

0.799

Oocytes retrieved (n)

Fertilization mode (%)

13.59 ± 3.48

13.39 ± 3.44

0.753

0.255

IVF

74 (91.4)

39 (84.8)

ICSI

7 (8.6)

7 (15.2)

Endometrial thickness on ET day (cm)

11.57 ± 2.12

11.76 ± 1.97

0.629

No. of embryos transferred, n (%)

0.745

1

80/82 (97.6)

46/46 (100.0)

2

2/82 (2.4)

0

MII oocytes rate (%)

92.01% (1013/1101)

93.18% (574/616)

0.378

2PN oocytes rate (%)

74.24% (804/1083)

76.19% (464/609)

0.374

Cleavage rate of 2PN oocytes (%)

98.89% (795/804)

98.92% (459/464)

0.945

Available embryo rate at Day 3 (%)

89.69% (713/795)

88.02% (404/459)

0.362

High-quality embryo rate at Day 3 (%)

41.89% (333/795)

42.48% (195/459)

0.837

Blastocyst formation rate (%)

77.03% (664/862)

81.06% (398/491)

0.083

High-quality embryo rate for transplantation

58.54% (48/82)

69.57% (32/46)

0.216

Available blastocyst formation rate (%)

60.79% (524/862)

66.19% (325/491)

0.014*

Day 5 available blastocyst formation rate (%)

46.98% (405/862)

54.58% (268/491)

0.007*