Table 5

 Comparison of birth weight of infants and proportion of low birth weight (LBW)* by smoking status of pregnant women (n = 9499)

Smoking statusNumber (%)Mean (SD) birth weight (g)LBW infantsOR‡(95% CI)OR§95% CI
NumberRate (%)
*LBW defined as birth weight less than 2500 g.
†Mean birth weight is statistically smaller than that of never smoking mothers and that of quitting mothers, p<0.05.
‡Odds ratios (OR) of quitting mothers or non-quitting mothers in having LBW infants, when compared with proportion of LBW infants by non-smokers.
§Adjusted for mothers’ age, educational level of mothers, sex of infants, parity, and alcohol drinking habit.
Never smoking mothers8892 (93.6%)3184 (430)4304.81.01.0
Quitting mothers400 (4.2%)3195 (447)235.81.1(0.9 to 1.4)1.1(0.9 to 1.4)
Non-quitting mothers207 (2.2%)3027 (450)†178.21.8(1.1 to 2.9)1.7(1.0 to 2.8)