Table 1 General characteristics of the study population (n = 896)

Mean age at retrieval (y.o.)

36.1 ± 4.1

35.9 ± 4.4

0.966 ^mw

Smoking habits (%)

82 (10.4)

14 (12.8)

0.442^k

BMI (kg/m²)

23.6

23.8

0.485 ^mw

Type of infertility

0.123^k

Primary

528 (67.1)

65 (59.6)

Secondary

259 (32.9)

44 (40.4)

Main causes of infertility*

Endometriosis

346 (44.0)

38 (34.9)

0.072^k

Male factor

299 (38.0)

48 (44.0)

0.225^k

Tubal factor

145 (18.4)

12 (11.0)

0.056^k

Ovulatory disorders

48 (6.1)

3 (2.8)

0.158^k

Idiopathic

70 (8.9)

13 (11.9)

0.309^k

Ovarian reserve

Day 3 FSH (IU/L)

7.1 ± 2.3

7.6 ± 2.9

0.132 ^mw

Day 3 estradiol (pg/mL)

51.1 ± 84.3

47.1 ± 19.2

0.349 ^mw

AMH (ng/mL)

2.8 ± 2.2

1.8 ± 1.4

< 0.001 ^mw

AFC (mean)

17.1 ± 10.8

13.9 ± 7.5

0.006 ^mw

IVF/ICSI rank (n)

1.6 ± 1.1

1.9 ± 1.1

< 0.001 ^mw

Endometrial thickness (mm)

9.0 ± 1.9

9.4 ± 2.6

0.035 ^mw

Top- or good-quality embryo transfer^a

542 (68.9)

82 (75.2)

0.176^k

Top-quality embryo^a

26 (3.3)

0 (0.0)

0.054^k

Type of endometrial preparation (FET cycle only) (%)

NA

HRT cycle

547 (69.6)

NA

HRT cycle + downregulation with GnRHa

152 (19.3)

NA

Natural cycle

72 (9.1)

NA

Stimulated cycle

16 (2.0)

NA