Relationship between individual NO
exposure during the first trimester and anthropometric measures at birth. Graphical estimation of the association and 95% confidence intervals for the non-linear model with lower AIC (degrees of freedom: df). (A). Birth weight (gr) and NO2 exposure (3 df) B). Birth length (cm) and NO2 exposure (4 df). (C). Birth head circumference (cm) and NO2 exposure (4 df). Footnote for Figure 2(C): For birth head circumference the model with the best adjustment was the linear model.