Table 1 Comparison of clinical characteristics and IVF outcome between the OHSS and non-OHSS groups

Age of patients (y)

29.39 ± 2.56

28.94 ± 4.04

0.613

BMI (kg/m²)

23.25 ± 2.80

23.40 ± 2.91

0.842

Infertility duration(y)

3.62 ± 2.61

3.81 ± 2.66

0.786

Basal serum FSH (mIU/ml)

6.20 ± 1.10

6.93 ± 1.76

0.074

Basal serum LH (mIU/ml)

6.81 ± 5.07

4.26 ± 1.67

0.020^a

Basal serum E2 (pg/ml)

29.45(21.39–34.61)

25.02(13.35–39.62)

0.671

Basal serum P4 (ng/ml)

0.57(0.38–0.79)

0.54(0.38–0.67)

0.414

Basal serum PRL (ng/ml)

18.24 ± 7.56

18.21 ± 7.94

0.986

Basal serum T (ng/ml)

0.31 ± 0.16

0.25 ± 0.13

0.279

Antral follicle count(n.)

16.89 ± 4.97

13.26 ± 4.75

0.146

Starting dose of Gonadotrophin (IU)

150(112.5–150)

150(112.5–225)

0.174

Gonadotrophin duration (d)

11.54 ± 1.30

10.77 ± 1.91

0.089

Total Gonadotrophin dose (IU)

1425.00(1190.63–1678.13)

1500(1275.00–2125.00)

0.248

Serum E2 on hCG day (pg/ml)

7667.46 ± 2821.10

4076.58 ± 2343.74

<0.001^a

Serum P4 on hCG day (ng/ml)

1.10 ± 0.42

0.69 ± 0.33

<0.001^a

Serum E2 on OPU day (pg/ml)

4306.81 ± 1683.73

2402.39 ± 1666.98

<0.001 ^a

Serum P4 on OPU day (ng/ml)

22.65(11.97–34.61)

7.28(5.37–12.08)

<0.001 ^a

Larger than 18 mm before injection (n.)

4(3–5)

4(3–5.25)

0.201

Total oocytes obtained (n.)

20.46 ± 5.83

10.36 ± 4.87

<0.001^a

No. of 2PN oocytes

14.15 ± 5.49

7.58 ± 4.07

<0.001^a

No. of 2PN cleavage embryos

13.65 ± 5.11

7.48 ± 4.12

<0.001^a

High-quality embryos (n.)

6.31 ± 3.00

3.45 ± 2.50

<0.001 ^a

2PN oocytes ratio

0.74 ± 0.04

0.69 ± 0.03

0.351

2PN cleavage embryos ratio

0.72 ± 0.04

0.67 ± 0.03

0.32

Total embryos ratio

0.37 ± 0.03

0.42 ± 0.04

0.245

High-quality embryos ratio

0.35 ± 0.04

0.32 ± 0.03

0.596

FF melatonin(ng/ml)

35.94 ± 10.18

23.93 ± 10.94

<0.001^a