Table 1 Patients’ characteristics in D5 group and D6 group

Age when OPU(years)

32.6(4.8)

32.8(4.9)

0.657

Basal follicle stimulating hormone (IU/L)

6.6(2.2)

6.7(1.7)

0.569

Body mass index(Kg/m²)

22.1(3.5)

22.5(3.3)

0.312

Type of infertility

0.963

Primary infertility(%)

216(54.3)

67(54.0)

Secondary infertility(%)

182(45.7)

57(46.0)

Infertility duration(years)

4.8(3.3)

5.0(4.0)

0.622

No.of embryos transferred

1.0(1.0–1.0)

1.0(1.0–2.0)

 < 0.001

No.of high- quality embryos transferred

1.0(1.0–1.0)

1.0(1.0–2.0)

0.965

Fertilization methods

0.182

IVF(%)

285(71.6)

81(65.3)

ICSI (%)

113(28.4)

43(34.7)

Diagnosed with PCOS (%)

69(17.3)

14(11.3)

0.108

Gestation age when abortion (weeks)

8.0(1.7)

8.0(1.7)

0.800