Table 4 Results of the logistic regression model comparing preterm low birth weight vs term normal birth weight newborns

Outcome (preterm-low birth weight = 1, normal birth weight = 0)

Log-likelihood = -152.829, chi-square= 145.15, P value < 0.0001

Course of pregnancy (dichotomous: 0 = physiologic, 1 = pathologic)

11.49

4.9

4.98–26.48

< 0.0001

Number of fetuses (dichotomous: 0 = single, 1 = multiple)

23.8

12.98

8.15–69.31

< 0.0001

Type of delivery (dichotomous: 0 = eutocic, 1 = caesarean)

2.82

0.88

1.53–5.21

0.001

Marital status of mother (dichotomous: 0 = other, 1 = married)

4.49

3.3

1.06–18.96

0.041

Number of echographies (continuous)

0.86

0.08

0.71–1.03

0.108

Education level of mother (dichotomous: 0 = mother not a high school graduate, 1 = a high school graduate or more)

0.62

0.2

0.33–1.15

0.131

Maternal age

< 25

1.0*

25–29

0.46

0.25

0.16–1.32

0.151

30–34

0.88

0.45

0.33–2.37

0.801

≥ 35

0.62

0.33

0.21–1.77

0.369

Amniocentesis (dichotomous: 0 = no, 1 = yes)

0.49

0.25

0.18–1.31

0.154

Birth's order (dichotomous: 0 = 1–4, 1 => 4)

3.53

3.9

0.4–30.85

0.255

Number of prenatal care visits (dichotomous: 0 = 0–4 not satisfactory, 1 => 4 satisfactory)

0.76

0.27

0.38–1.52

0.437

Size of municipality of residence, inhabitants (dichotomous: 0 =≤ 90.000 i.e. small town, 1 => 90.000, i.e. large town)

0.8

0.25

0.42–1.49

0.474

Newborn sex (dichotomous: 0 = female, 1 = male)

0.82

0.25

0.45–1.49

0.509

Social support during pregnancy (dichotomous: 0 = no, 1 = yes)

0.84

0.26

0.45–1.56

0.578

Occupation of mother

Work outside home

1.0*

Unemployed

1.21

0.63

0.44–3.34

0.709

Housewife

1.13

0.42

0.54–2.33

0.75

Number of cigarettes/day during pregnancy (continuous)

1

0.08

0.86–1.17

0.96