Table 1 Characteristics of included participants

Cycles

337

73

Female age at retrieval^% (y)

Female age at transfer^% (y)

32.60 ± 4.07

33.32 ± 4.08

31.77 ± 4.18

34.46 ± 3.90

0.980

0.415

BMI^% (kg/m²)

Duration of infertility^# (y)

Type of infertility

22.15 ± 3.07

4 (2–5)

21.50 ± 2.61

4 (2–7)

0.141

0.186

0.916

 Primary

 Secondary

187

150

41

32

Endometrial thickness^# (mm)

Blastocyst grade

10.3 (9.0-11.65)

10.8 (9.0–12.0)

0.345

0.904

 High-grade

 Low-grade

400

25

85

5

Average No. of embryos transferred^%

1.26 ± 0.44

1.23 ± 0.43

0.500