Exposure to drinking water THM and their association with low birth weight and small for gestational age in genetically susceptible women

Little is known about genetic susceptibility to individual trihalomethane (THM) in relation to adverse pregnancy outcomes. To investigate whether the polymorphisms of metabolic genes GSTT1 and GSTM1 affect the association of maternal exposure to THM with low birth weight (LBW) and small for gestational age (SGA) risk. We conducted a nested case-control study of 682 pregnant women in Kaunas (Lithuania) and using individual information on drinking water, ingestion, showering and bathing, and uptake factors of THMs in blood, estimated an internal dose of THM. We used logistic regression to evaluate the relationship between internal THM dose, birth outcomes and individual and the joint (modifying) effects of metabolic gene polymorphisms, controlling for gestational age, marital status, education, smoking, alcohol consumption, body mass index, blood pressure, ethnic group, pregnancy history, infant gender, and birth year. THM exposure during entire pregnancy and specific trimesters slightly increased LBW risk. When considering both THM exposure and maternal genotypes, the largest associations were found for third trimester among total THM (TTHM) and chloroform exposed women with the GSTM1–0 genotype (OR 4.37; 95% CI, 1.36–14.08 and OR 5.06; 95% CI, 1.50–17.05, respectively). A test of interaction between internal THM dose and GSTM1–0 genotype suggested modifying effect of exposure to chloroform and bromodichlormethane on LBW risk. However, the effect on SGA was not statistically significant. These data suggest that THM internal dose may affect fetal growth and that maternal GSTM1 genotype modifies the THM exposure effects on LBWAplinkotyros katedraBiologijos katedraVytauto Didžiojo universiteta