Table 1 The comparison of characteristics and COH parameters between pregnant and non-pregnant women

Age (years)

32.2 ± 4.0

32.7 ± 3.8

0.352

31.9 ± 4.0

31.1 ± 4.1

0.003

BMI (kg/m²)

22.4 ± 2.9

2.2 ± 2.6

0.696

9.4 ± 1.5

9.4 ± 1.4

0.312

Pregnancy history

0.6 ± 0.5

0.6 ± 0.5

0.628

9.0 ± 3.9

9.0 ± 3.8

0.930

Basal FSH levels (IU/L)

11.8 ± 1.9

11.6 ± 1.7

0.424

7.5 ± 1.4

7.5 ± 1.4

0.947

Basal LH levels (IU/L)

5.4 ± 1.9

5.0 ± 2.1

0.260

4.3 ± 2.2

4.3 ± 2.2

0.974

Basal E₂ levels (pg/ml)

43.3 ± 20.8

41.6 ± 18.3

0.581

43.3 ± 30.5

41.2 ± 31.4

0.300

Basal T levels (ng/dl)

48.3 ± 17.3

40.8 ± 18.1

0.008

47.8 ± 18.9

47.7 ± 19.9

0.907

Antral follicle count

9.8 ± 4.3

8.6 ± 4.6

0.099

11.6 ± 5.5

11.2 ± 5.7

0.217

Starting dose of gonadotropins (IU)

223.3 ± 54.6

228.1 ± 67.3

0.617

203.6 ± 36.7

198.6 ± 40.7

0.053

Number of oocytes retrieved

10.0 ± 4.4

9.0 ± 4.7

0.171

12.4 ± 5.4

12.4 ± 5.3

0.999

Number of follicles >14 mm

7.8 ± 3.5

7.1 ± 3.5

0.176

9.0 ± 3.9

9.0 ± 3.8

0.761

Days of stimulation

9.7 ± 1.6

10.5 ± 1.9

0.002

9.4 ± 1.5

9.4 ± 1.4

0.744

Total dose of gonadotropins (IU)

2477.8 ± 873.9

2936.1 ± 1249.9

0.010

2174.2 ± 826.8

2042.3 ± 728.7

0.012

Endometrial thickness on HCG day (cm)

1.1 ± 0.2

1.1 ± 0.2

0.521

1.0 ± 0.2

1.1 ± 0.2

0.001

Fertilization rate

0.8 ± 0.2

0.7 ± 0.2

0.202

0.7 ± 0.2

0.7 ± 0.2

0.615

Number of embryos cryopreserved

3.3 ± 2.9

2.4 ± 2.4

0.034

3.9 ± 3.4

4.1 ± 3.2

0.256

Number of good quality embryos

5.6 ± 2.9

4.5 ± 2.5

0.015

6.0 ± 3.4

6.3 ± 3.2

0.219