Frequency characteristics for predictor, outcome and control variables
| Smoking in pregnancy | p Test for trend | ||||
| Never smoked | 1–10 cigarettes daily pre-pregnancy* | 11+ cigarettes daily pre-pregnancy* | Smoked before and during pregnancy | ||
| n (%) | n (%) | n (%) | n (%) | ||
| n=1137 (41.2%) | n=464 (16.8%) | n=424 (15.4%) | n=733 (26.6%) | ||
| Gender of child | 0.062 | ||||
| Male | 604 (43.5) | 215 (15.5) | 223 (16.1) | 346 (24.9) | |
| Female | 532 (39.3) | 247 (18.2) | 196 (14.5) | 380 (28.0) | |
| Maternal age at conception | <0.001 | ||||
| <20 years | 60 (22.1) | 54 (19.9) | 36 (13.3) | 121 (44.6) | |
| 20–24.9 years | 193 (32.8) | 94 (16.0) | 94 (16.0) | 207 (35.2) | |
| 25–29.9 years | 366 (44.1) | 149 (18.0) | 111 (13.4) | 203 (24.5) | |
| 30–34.9 years | 337 (48.4) | 106 (15.2) | 113 (16.2) | 140 (20.1) | |
| 35+ years | 177 (49.6) | 59 (16.5) | 65 (18.2) | 56 (15.7) | |
| Maternal education at pregnancy | <0.001 | ||||
| ≤Year 10 | 353 (30.2) | 181 (15.5) | 183 (15.7) | 452 (38.7) | |
| Year 11 | 190 (37.7) | 85 (16.9) | 87 (17.3) | 142 (28.2) | |
| Year 12+ | 591 (55.0) | 196 (18.2) | 151 (14.1) | 136 (12.7) | |
| Father living with family in pregnancy | <0.001 | ||||
| Yes | 1058 (44.0) | 413 (17.2) | 372 (15.5) | 563 (23.4) | |
| No | 79 (22.7) | 50 (14.4) | 50 (14.4) | 169 (48.6) | |
| Low family income in pregnancy | <0.001 | ||||
| ≤$24 000 per annum | 273 (33.8) | 113 (14.0) | 116 (14.4) | 306 (37.9) | |
| >$24 000 per annum | 809 (45.9) | 314 (17.8) | 279 (15.8) | 362 (20.5) | |
| Stress events in pregnancy | <0.001 | ||||
| None | 247 (45.6) | 103 (19.0) | 90 (16.6) | 102 (18.8) | |
| One to two events | 453 (44.7) | 177 (17.5) | 152 (15.0) | 232 (22.9) | |
| Three+ events | 323 (35.2) | 146 (15.9) | 145 (15.8) | 304 (33.1) | |
| Alcohol intake | <0.001 | ||||
| None | 721 (48.0) | 242 (16.1) | 203 (13.5) | 336 (22.4) | |
| ≤One drink per week | 265 (41.0) | 112 (17.3) | 108 (16.7) | 161 (24.9) | |
| Two to six drinks per week | 125 (25.5) | 96 (19.6) | 92 (18.8) | 177 (36.1) | |
| Daily+ | 26 (22.0) | 14 (11.9) | 21 (17.8) | 57 (48.3) | |
Missing cases not included in analysis unless stated otherwise, valid row percentages presented.
↵* No longer smoking by 18 weeks gestation.