Table 4 Characteristics of IUI cycles according to different infertility duration after Propensity-Score Matching

Female age, years

30.9 ± 3.4

31.1 ± 3.2

0.22

Male age, years

32.3 ± 4.4

32.8 ± 3.9

0.24

BMI, kg/m²

23.1 ± 3.6

23.3 ± 3.7

0.35

Baseline FSH, IU/L

7.2 ± 2.1

7.2 ± 1.9

0.42

AFC, n

18.2 ± 7.2

18.1 ± 7.5

0.92

Type of infertility

0.96

Primary infertility, n

Secondary infertility, n

718 (71.7%)

284 (28.3%)

722 (71.9%)

282 (28.1%)

IUI cycles, n

1.6 ± 0.7

1.6 ± 0.7

0.97

Protocol

0.68

Natural cycle

141 (14.1%)

157 (15.6%)

CC for OI cycle

254 (25.3%)

240 (23.9%)

LE for OI cycle

550 (54.7%)

542 (54.0%)

HMG for OI cycle

59 (5.9%)

65 (6.5%)

Endometrial thickness, mm

10.1 ± 2.0

10.1 ± 1.9

0.82

Number of IUI, n

0.34

1

2

180 (18.0%)

824 (82.0%)

164 (16.3%)

840 (83.7%)

Number of progressive motility spermatozoa after treatment, million

16.7 ± 11.5

16.3 ± 10.9

0.32

Clinical pregnancy rate

19.6% (197)

15.0% (151)

< 0.01

Early miscarriage rate

16.8% (33)

18.5% (28)

0.77

Live birth rate

15.5% (156)

12.0% (120)

0.02