TABLE 3.
ANCOVA Models for Birth Weight and BDNF
| Model 1 |
Model 2 |
|||||||
| df | F | Effect size | Estimated p | df | F | Effect size | Estimated p | |
| Birth weight | ||||||||
| Intercept | 1 | 6894.2 | 1.000 | < 0.001 | 1 | 7182.4 | 1.000 | < 0.001 |
| Hg in cord blood | 1 | 0.703 | 0.083 | 0.594 | 1 | 1.529 | 0.153 | 0.352 |
| Total PCB | 1 | 1.110 | 0.056 | 0.821 | 1 | 0.792 | 0.070 | 0.674 |
| Maternal smokinga | 1 | 23.475 | 0.998 | < 0.001 | ||||
| Sex | 1 | 13.018 | 0.944 | < 0.001 | 1 | 17.133 | 0.983 | < 0.001 |
| Gestational ageb | 4 | 12.781 | 0.999 | < 0.001 | 4 | 12.437 | 0.999 | < 0.001 |
| Sex × gestational age | 4 | 1.056 | 0.311 | 0.416 | 4 | 0.876 | 0.226 | 0.527 |
| BDNF | ||||||||
| Intercept | 1 | 364.1 | 1.000 | < 0.001 | 1 | 338.7 | 1.000 | < 0.001 |
| Hg in cord blood | 1 | 0.355 | 0.075 | 0.645 | 1 | 0.564 | 0.095 | 0.535 |
| Total PCB | 1 | 0.536 | 0.054 | 0.856 | 1 | 0.428 | 0.051 | 0.917 |
| Maternal smokinga | 1 | 3.985 | 0.521 | 0.044 | ||||
| Sex | 1 | 1.490 | 0.223 | 0.232 | 1 | 1.966 | 0.281 | 0.168 |
| Gestational ageb | 4 | 3.729 | 0.890 | 0.005 | 4 | 3.985 | 0.912 | 0.003 |
| Sex × gestational age | 4 | 2.703 | 0.745 | 0.031 | 4 | 2.877 | 0.775 | 0.023 |
a
Maternal smoking was scored with increasing values for every additional five cigarettes smoked per day (i.e., 0 = nonsmoker, 1 = 1–5 cigarettes per day, 2 = 5–10 cigarettes per day, etc.).
b
Based on the inclusion criteria, the gestational age at delivery was divided into five categories, i.e., gestational weeks 38, 39, 40, 41, and 42.