Comparison of characteristics between smokers and non-smokers with dietary data available (n=398)
| All women (n=398)* | Smokers (n=50) | Non-smokers (n=348)† | P values | |
| Age (years) (mean±SD) | 30.5±5.6 | 27.0±6.44 | 31.0±5.3 | <0.001 |
| BMI (kg/m2) (mean±SD) | 25.9±5.4 | 25.3±4.7 | 26.0±5.5 | 0.418 |
| Obese (%) | 19.2 (76) | 22 (11) | 18.7 (65) | 0.323 |
| Nulliparous (%) | 45.5 (181) | 46.0 (23) | 45.4 (158) | 0.937 |
| Irish-born (%) | 76.9 (306) | 82 (41) | 76.1 (265) | 0.739 |
| Alcohol intake during pregnancy (%) | 4.8 (19) | 6.1 (3) | 4.7 (16) | 0.863 |
| Birth weight (g) (mean±SD) | 3426.9±586.1 | 3134.4±622.1 | 3469.46±569.2 | <0.001 |
Significance level—0.05, statistical tests used— χ2 test for categorical variables and independent samples t-test for continuous variables).
*Of the 398 women studied, delivery outcomes were available on 378; 330 who were non-smokers and 48 who were current smokers. The remaining women delivered elsewhere.
†As dietary composition was similar between never smokers and former smokers (online supplementary tables 1 and 2), they are combined into one ‘non-smokers’ group.
BMI, body mass index.