Table 4 Prevalence of environmental tobacco exposure: maternal report versus biomarker-based at birth and at 4 years of age
| Â | At delivery N = 415 | 4th year N = 306 | p-value* |
|---|---|---|---|
ETS exposure: | Â | Â | Â |
By questionnaire: | Â | Â | Â |
Active maternal smoking (NDI >0) (%) | 144 (34.7) | 148 (48.4) | <0.001 |
Passive exposure(DEN >0) (%) | 175 (42.2) (mother DEN) | 95 (31.0) (child DEN) | <0.01 |
By biomarker: | Umbilical cord blood | Child Urine | Â |
   0 – 1 ng/mL (%) (no exposure) | 45 (10.8) | 5 (2.0) | <0.001 |
   1 – 14 ng/mL (%) (low) | 228 (55.0) | 186 (60.4) | 0.02 |
   >14 ng/mL (%) (medium and high) | 142 (34.2) | 115 (37.6) | 0.35 |