Table 2 Logistic regression analyses examining the association between preterm birth or low birth weight, active maternal smoking, total smoke exposure and Perceived Stress Scale scores (complete case and imputed, without interaction, including interaction)

Active maternal smoke exposure

1.63

(1.07–2.48)

0.93

(0.25–3.49)

1.36

(0.76–2.43)

1.21

(0.67–2.18)

0.65

(0.25–1.74)

0.89

(0.40–1.97)

Perceived Stress Scale score (PSS)

1.03

(1.01–1.06)

1.03

(1.001–1.06)

1.03

(1.00-1.06)

1.02

(0.99–1.05)

1.01

(0.97–1.05)

1.01

(0.98–1.05)

Interaction: Active maternal smoke exposure and PSS score

1.03

(0.95–1.11)

1.01

(0.98–1.04)

1.03

(0.99–1.08)

1.02

(0.98–1.06)

Total smoke exposure

1.56

(1.07–2.28)

1.62

(0.63–4.17)

1.55

(0.65–3.69)

1.52

(0.93–2.50)

2.64

(0.94–7.40)

2.13

(0.85–5.33)

Perceived Stress Scale score (PSS)

1.03

(1.01–1.06)

1.04

(1.01–1.07)

1.03

(1.01–1.06)

1.02

(0.99–1.05)

1.03

(0.98–1.07)

1.03

(0.99–1.06)

Interaction: Total smoke exposure and PSS score

0.99

(0.94–1.05)

1.00

(0.95–1.05)

0.96

(0.90–1.03)

0.98

(0.92–1.04)