Table 3 Characteristics of IUI cycles according to different infertility duration

Female age, years

29.1 ± 3.5

31.1 ± 3.2

< 0.01

Male age, years

30.4 ± 4.2

32.8 ± 3.9

< 0.01

BMI, kg/m²

23.0 ± 3.5

23.3 ± 3.7

< 0.01

Baseline FSH, IU/L

7.2 ± 2.0

7.2 ± 1.9

0.82

AFC, n

19.3 ± 7.8

18.1 ± 7.5

< 0.01

Type of infertility

0.17

Primary infertility, n

Secondary infertility, n

2973 (69.7%)

1291 (30.3%)

722 (71.9%)

282 (28.1%)

IUI cycles, n

1.6 ± 0.8

1.6 ± 0.7

0.35

Protocol

0.74

Natural cycle

623 (14.6%)

157 (15.6%)

CC for OI cycle

1017 (23.9%)

240 (23.9%)

LE for OI cycle

2316 (54.3%)

542 (54.0%)

HMG for OI cycle

308 (7.2%)

65 (6.5%)

Endometrial thickness, mm

10.1 ± 2.0

10.1 ± 1.9

0.77

Number of IUI, n

0.36

1

2

748 (17.5%)

3516 (82.5%)

164 (16.3%)

840 (83.7%)

Number of progressive motility spermatozoa after treatment, million

17.4 ± 11.3

16.3 ± 10.9

0.33

Clinical pregnancy rate

19.6% (834)

15.0% (151)

< 0.01

Early miscarriage rate

15.3% (128)

18.5% (28)

0.39

Live birth rate

16.1% (688)

12.0% (120)

< 0.01