Fig. 5

The effects of maternal smoking in combination with maternal NQO1 genotype on infants’ birth size. Adjusted for maternal age, height, weight before pregnancy, weight gain during pregnancy, alcohol consumption during pregnancy, parity, infant gender, gestational age, and household income. Interaction in multiple linear regression models was defined as product terms for the product of the dummy independent variables: maternal smoking status (nonsmoker, quitter or smoker) and genotype (wild or mutant). β represents the product term for smoker × wild genotype. NQO1 NAD(P)H: quinone oxidoreductase 1, Pro proline, Ser serine This figure was constructed by using the data from previous study by Sasaki et al. [57]