Table 1 Maternal, pregnancy and delivery variables, by mode of conception (n = 2529)

Age ≥35 years

703

(31.9)

69

(45.4)

<0.001

Country of origin other than Italy

541

(23.2)

16

(9.9)

<0.001

Upper secondary/university education

1206

(59.6)

108

(78.3)

<0.001

Previous births

937

(40.4)

30

(18.5)

<0.001

Plurality

 Twin

264

(11.6)

75

(46.0)

 Triplet

14

(0.6)

42

(25.8)

<0.001

 Quadruplet

0

2

(1.2)

Complications of pregnancy

 Disorders of placentation¹

731

(31.4)

46

(28.4)

0.431

 Inflammation/infection²

1446

(61.9)

109

(67.3)

0.170

Gestational age at delivery (weeks)

 <26

345

(14.6)

28

(17.2)

0.606

 26-27

412

(17.4)

23

(14.1)

 28-29

591

(25.0)

39

(23.9)

 30-31

1018

(43.0)

73

(44.8)

Delivery at tertiary centre

2108

(89.1)

154

(94.5)

0.031

Any antenatal steroids

1741

(76.4)

131

(81.9)

0.111

Spontaneous onset of labour

1014

(43.8)

84

(52.8)

0.027

Caesarean delivery

1687

(71.6)

130

(79.7)

0.025