Table 1 Main patient characteristics.

Number of patients

170

576

Number of embryotransfers per patient

1.3 ± 0.6

1.4 ± 0.8

P = 0.26 (NS)

Age at ovum pick, mean ± SD

33.6 ± 4.4

32.7 ± 4.8

P = 0.06 (NS)

BMI

24.7 ± 3.5

24.5 ± 4.0

P = 0.25 (NS)

Endometrium thickness

9.3 ± 2.0

8.8 ± 2.0

P = 0.03*

Endometrium thickness ≥7 mm

89/92 (96.7%)

374/415 (90.1%)

χ² = 4.2

P = 0.04*

Endometrium thickness < 7 mm

3/92 (3.3%)

41/415 (9.88)

Primary diagnosis

PCOS

8/170 (4.7%)

55/576 (9.6%)

Tubal factor

17/170 (10.0%)

38/576 (7.4%)

Male factor

41/170 (24.1%)

167/576 (29.0%)

Endometriosis

14/170 (8.3%)

70/576 (12.2%)

Uterine factor

0

4/576 (0.7%)

P = 0.34 (NS)

Single

23/170 (13.5%)

73/576 (12.7%)

Causa ovarialis

6/170 (3.5%)

18/576 (3.1%)

No specification

0

19/576 (3.3%)

Unexplained

61/171 (35.9%)

131/576 (22.7%)

Others

0

1/576 (0.2%)

Fertilization method

IVF

ICSI

104 (61.2%)

66 (38.8%)

310 (53.8%)

266 (46.2%)

P = 0.10 (NS)

Number of frozen blastocysts, mean ± SD

2.6 ± 1.8

2.3 ± 1.7

P = 0.11 (NS)