Characteristics (exposures) at 3 months of age of infants of mothers who did and did not smoke in pregnancy
| Characteristics | Mothers smoked in pregnancy(n = 33) | Mothers did not smoke in pregnancy(n = 54) | p Value† |
|---|---|---|---|
| SVD, spontaneous vertex delivery; URTI, upper respiratory tract infection. | |||
| *p<0.05 between the two groups. | |||
| †Pearson’s χ2 test (categorical) or Mann-Whitney U test (continuous) were used to determine differences between groups. | |||
| ‡Data were only available on a subgroup of the total population. | |||
| Perinatal characteristics | |||
| Method of delivery | |||
| SVD | 25/33 | 40/54 | 0.861 |
| Caesarean | 8/33 | 14/54 | − |
| Mean (SE) gestational age (days) | 279.8 (1.6) | 277.1 (1.0) | 0.161 |
| Mean (SE) birth weight (g) | 3335.9 (66.8) | 3451.4 (53.7) | 0.185 |
| Mean (SE) birth length (cm) | 49.5 (0.39) | 49.5 (0.26) | 0.979 |
| Mean (SE) head circumference (cm) | 34.4 (0.24) | 34.6 (0.17) | 0.429 |
| Median (IQR) 5 min Apgar score | 9 (9, 9) | 9 (9.0, 9.25) | 0.623 |
| Other factors | |||
| Education level | |||
| Above trade or technical qualification | 18/26 (69.2%) | 36/51 (70.5%) | 0.117 |
| URTI‡ | 4/18 (22.2%) | 8/41 (19.5%) | 0.812 |
| Exposure to passive smoke (partner or other)‡ | |||
| Nil | 9/23 (39.1%) | 35/50 (70.0%) | 0.136 |
| Light | 12/23 (52.2%) | 12/50 (24.0%) | – |
| Moderate | 2/23 (8.7%) | 3/50 (6.0%) | – |
| Maternal allergy | 20/33 (60.6%) | 25/54 (46.3%) | 0.195 |
| Infant feeding | |||
| Breastfed (ever) | 23/23 (100.0%) | 48/50 (96.0%) | 0.331 |
| Formula fed (ever) | 22/23 (95.7%) | 35/50 (70.0%) | 0.014* |
| No of siblings | |||
| 0 | 13/23 (56.5%) | 15/50 (30.0%) | 0.070 |
| 1 | 6/23 (26.1%) | 23/50 (46.0%) | |
| 2+ | 4/23 (17.4%) | 12/50 (24.0%) | |
| Exposure to pets | 6/23 (26.1%) | 20/50 (40.0%) | 0.202 |
| Child care | 14/23 (60.9%) | 38/50 (76.0%) | 0.185 |