Table 4 The results of multivariate logistic analyses for selection of formula feeding presented as odds ratios and 95% confidence intervals

Birth year

1968–1984 (reference: 1985–2003)

3.29 (2.57–4.21)

3.79 (2.96–4.86)

2.61 (2.16–3.14)

2.70 (2.23–3.27)

2.24 (1.82–2.76)

2.30 (1.87–2.82)

Birthweight

<2,000 g (reference: ≥2,000 g)

Not selected

Not selected

–

–

–

–

Maternal age

≥35 years (reference: <35 years)

1.54 (1.08–2.20)

1.51 (1.05–2.15)

–

1.34 (1.02–1.77)

–

–

Gestational age

<37 weeks (reference: ≥37 weeks)

1.50 (1.14–1.97)

Not selected

1.28 (1.06–1.56)

Not selected

1.36 (1.10–1.67)

1.30 (1.06–1.61)

Sex

Male (reference: female)

not selected

–

–

–

–

–

Zygosity

Monozygotic (reference: dizygotic)

–

–

–

–

Not selected

–

Presentation

Non-vertex (reference: vertex)

–

Not selected

–

–

–

–

Use of incubator

Yes (reference: no)

1.34 (1.03–1.74)

1.92 (1.50–2.46)

–

1.35 (1.12–1.62)

–

Not selected

Neonatal asphyxia

Severe or mild (reference: no)

–

Not selected

–

–

–

–