title: Individual exposures to drinking water trihalomethanes, low birth weight and small for gestational age risk: a prospective Kaunas cohort study.
abstract: BACKGROUND
  Evidence for an association between exposure during pregnancy to trihalomethanes (THMs) in drinking water and impaired fetal growth is still inconsistent and inconclusive, in particular, for various exposure routes. We examined the relationship of individual exposures to THMs in drinking water on low birth weight (LBW), small for gestational age (SGA), and birth weight (BW) in singleton births.
  
  
  METHODS
  We conducted a cohort study of 4,161 pregnant women in Kaunas (Lithuania), using individual information on drinking water, ingestion, showering and bathing, and uptake factors of THMs in blood, to estimate an internal dose of THM. We used regression analysis to evaluate the relationship between internal THM dose and birth outcomes, adjusting for family status, education, smoking, alcohol consumption, body mass index, blood pressure, ethnic group, previous preterm, infant gender, and birth year.
  
  
  RESULTS
  The estimated internal dose of THMs ranged from 0.0025 to 2.40 mg/d. We found dose-response relationships for the entire pregnancy and trimester-specific THM and chloroform internal dose and risk for LBW and a reduction in BW. The adjusted odds ratio for third tertile vs. first tertile chloroform internal dose of entire pregnancy was 2.17, 95% CI 1.19-3.98 for LBW; the OR per every 0.1 μg/d increase in chloroform internal dose was 1.10, 95% CI 1.01-1.19. Chloroform internal dose was associated with a slightly increased risk of SGA (OR 1.19, 95% CI 0.87-1.63 and OR 1.22, 95% CI 0.89-1.68, respectively, for second and third tertile of third trimester); the risk increased by 4% per every 0.1 μg/d increase in chloroform internal dose (OR 1.04, 95% CI 1.00-1.09).
  
  
  CONCLUSIONS
  THM internal dose in pregnancy varies substantially across individuals, and depends on both water THM levels and water use habits. Increased internal dose may affect fetal growth.
authors.affiliation: Department of Environmental Sciences, Vytautas Magnus University, Kaunas, Lithuania. r.grazuleviciene@gmf.vdu.lt
authors.forename: Regina
authors.initials: R
authors.lastname: Grazuleviciene
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Nieuwenhuijsen
authors.forename: Jone
authors.initials: J
authors.lastname: Vencloviene
authors.forename: Maria
authors.initials: M
authors.lastname: Kostopoulou-Karadanelli
authors.forename: Stuart W
authors.initials: SW
authors.lastname: Krasner
authors.forename: Asta
authors.initials: A
authors.lastname: Danileviciute
authors.forename: Gediminas
authors.initials: G
authors.lastname: Balcius
authors.forename: Violeta
authors.initials: V
authors.lastname: Kapustinskiene
mesh_terms: D001724:Birth Weight; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008097:Lithuania / Q000453:epidemiology; D018811:Maternal Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011446:Prospective Studies; D012044:Regression Analysis; D018570:Risk Assessment; D012959:Socioeconomic Factors; D022882:Trihalomethanes / Q000032:analysis / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D014881:Water Supply
chemical_list: D022882:Trihalomethanes; D014874:Water Pollutants, Chemical