The effects of maternal smoking in combination with maternal PAHs-metabolism-related genetic polymorphisms on infants’ birth size. Adjusted for maternal age, height, weight before pregnancy, alcohol consumption during pregnancy, history of delivery, newborn sex, gestational weeks and household income. *p < 0.05, **p < 0.01 This figure was created by modifying a figure contained in our previous study by Sasaki et al. [56]