Methods. The design and THMs exposure of our population-based case-control study were presented recently (Levallois et al, 2012). Cases were term single neonates with birth weight 10th percentile) per case were chosen among births from the same calendar week. Exposure of mothers during the last trimester of pregnancy was based on intensive monitoring of DBPs of the water distribution systems serving the residences and a phone questionnaire of mothers two months after birth. DNA samples of infants and mothers were extracted from either blood or saliva samples. SNPs were genotyped with a multiplexed PCR reaction (MassARRAY SNP Multiplex Sequenom). Non-caucasian infants were excluded from the analysis. Odds Ratios (OR) were estimated by a non-conditional logistic regression on infant and mother genotype. Risk factors for IUGR were included in the model. Results. SNP genotypes were available for 298 cases and 1182 controls and their mothers. For total THMs ? 80?g/L, the adjusted OR for children with 1 or 2 variant alleles of CYP2E1 G1259C was estimated at 3.44 (95% CI: 0.63-18.57) in comparison with 1.20 (95%CI:0.80-1.73) for the wild type group (p value for interaction=0.325). Conclusion. We did not observe any significant effect modification of the CYP2E1 G1259C SNP on the association between DBP exposure and IUGR.