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Table 4 LBW adjusted odds ratio and BW change for gestational exposure to internal dose THMs

From: Individual exposures to drinking water trihalomethanes, low birth weight and small for gestational age risk: a prospective Kaunas cohort study

THM exposure Tertile limits (mg/d) LBW cases Non LBW Entire pregnancy ORa(95% CI) First trimester OR (95% CI) Second trimester OR (95% CI) Third trimester OR (95% CI)
TTHM b       
   0.0025-0.0386 40 1046 Reference Reference Reference Reference
   0.0386-0.3545 51 1099 1.77 (0.95-3.30) 1.94 (1.04-3.62) 1.71 (0.92-3.18) 2.31 (1.22-4.35)
   0.3545-2.4040 65 1040 2.13 (1.17-3.87) 2.29 (1.24-4.22) 2.06 (1.14-3.73) 2.12 (1.14-3.92)
Continuous (0.1 μg/d)    1.08 (1.01-1.16) 1.08 (1.01-1.16) 1.07 (1.00-1.15) 1.07 (1.00-1.15)
Change in BWc g    -49.3d (-146.3 - -1.5) -45.7d (-91.4-0.0) -45.3 (-92.8-2.2) -47.2d (-92.7 - -1.6)
Chloroform       
   0.0013-0.0249 40 1050 Reference Reference Reference Reference
   0.0249-0.2868 52 1093 2.06 (1.10-3.85) 2.30 (1.21-4.36) 1.79 (0.95-3.36) 2.12 (1.11-4.02)
   0.2868-2.1328 64 1042 2.17 (1.19-3.98) 2.41 (1.30-4.49) 2.13 (1.18-3.85) 2.13 (1.15-3.92)
Continuous (0.1 μg/d)    1.10 (1.01-1.19) 1.10 (1.02-1.18) 1.10 (1.01-1.18) 1.09 (1.01-1.18)
Change in BWc g    -59.3d (-114.8 - -3.7) -52.8d (-104.4 - -1.2) -53.4 (-108.2-1.3) -57.8d (-111.6 - -4.0)
CHBrCl2       
   0.0001-0.0124 45 1046 Reference Reference Reference Reference
   0.0124-0.0501 53 1093 1.83 (1.01-3.34) 1.93 (1.05-3.55) 1.95 (1.07-3.58) 1.64 (0.89-3.02)
   0.0501-0.3359 58 1046 1.64 (0.90-2.98) 2.06 (1.11-3.80) 1.82 (0.99-3.35) 1.80 (1.00-3.26)
Continuous (0.01 μg/d)    1.05 (1.00-1.11) 1.05 (1.00-1.11) 1.05 (0.99-1.11) 1.04 (1.00-1.10)
Change in BWe g    -28.2 (-63.2-6.9) -29.7 (-67.5-8.0) -27.7 (-63.2-7.7) -25.7 (-57.2-5.8)
CHBr2Cl       
   0.0000-0.0000 57 1058 Reference Reference Reference Reference
   0.0000-0.0039 49 1075 3.02 (1.23-7.40) 0.62 (0.28-1.37) 0.68 (0.31-1.46) 2.44 (1.05-5.70)
   0.0039-0.0644 50 1052 2.52 (1.00-6.36) 0.74 (0.37-1.49) 0.78 (0.36-1.67) 2.42 (1.03-5.66)
Continuous (0.01 μg/d)    1.18 (0.85-1.65) 1.06 (0.73-1.54) 1.16 (0.84-1.61) 1.23 (0.93-1.61)
Change in BWe g    -24.3 (-215.7-167.2) 15.5 (-197.0-228.1) -18.8 (-203.3-165.7) -45.9 (-207.6-114.8)
  1. aadjusted for squared gestational age, marital status, maternal education, chronic diseases, body mass index, blood pressure, smoking, alcohol consumption, previous preterm delivery, infant gender, and birth year.
  2. bTTHM, total trihalomethane; CHBrCl2, bromodichloromethane; CHBr2Cl, dibromochloromethane.
  3. cChange in birth weight in grams, of infants below 3,500 g, for every 1 μg/d increase in THMs internal dose.
  4. dp < 0.05.
  5. eChange in birth weight in grams, of infants below 3,500 g, for every 0.1 μg/d increase in THMs internal dose.