Non-parametric markers of ambient PAH concentration during various gestational periods and birth outcomesa.

aModel controls for gestational age (centered at mean and square term of the centered at mean), newborn gender, parity, and the mother's pre-pregnancy body mass index. C-section delivery is included only for the head circumference.bTo reduce multicollinearity in the models, the indicator variable was coded as the winter vs. other.cDirect measurement of personal exposure was determined using a personal monitor for 48-hour period. The exposure variable was coded in natural-log scale.