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Table 2 Distribution of Kaunas cohort study subjects for various characteristic by exposure

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

Risk factor/outcome Low THM N (%) Medium THM N (%) High THM N (%)
Maternal age    
   < 20 years 19 (1.8) 17 (1.5) 23 (2.1)
   20-29 years 652 (60.1) 688 (59.7) 658 (59.6)
   ≥ 30 years 414 (39.2) 447 (38.8) 423 (38.3)
Marital status    
   Married 876 (80.7) 958 (83.2) 910 (82.4)
   Not married 209 (19.3) 194 (16.8) 194 (17.6)
Maternal education    
   Primary school 59 (5.4) 50 (4.3) 57 (5.2)
   Secondary school 454 (41.8) 465 (40.4) 442 (40.0)
   University degree 572 (52.7) 637 (55.3) 605 (54.8)
   Maternal smoking    
   Nonsmoker 1003 (92.4) 1076 (93.4) 1031 (93.4)
   Smoker 82 (7.6) 76 (6.6) 73 (6.6)
Paternal smokinga    
   Nonsmoker 574 (53.4) 629 (55.4) 545 (49.8)
   Smoker 501 (46.6) 507 (44.6) 550 (50.2)
Alcohol consumptiona    
   No 1000 (92.2) 1094 (95.0) 1048 (94.9)
   Yes 85 (7.8) 58 (5.0) 56 (5.1)
Blood pressure    
   <140/80 mm/Hg 969 (89.3) 1020 (88.5) 977 (88.5)
   ≥140 or ≥ 90 mm/Hg 116 (10.7) 132 (11.5) 127 (11.5)
Ethnic group    
   Lithuanian 1054 (97.1) 1117 (97.0) 1082 (98.1)
   Other 31 (2.9) 35 (3.0) 21 (1.9)
Parity    
   No child 492 (45.3) 499 (43.3) 516 (46.7)
   ≥ 1 child 593 (54.7) 653 (56.7) 588 (53.3)
Infant gender    
   Male 559 (51.5) 611 (53.0) 544 (49.3)
   Female 526 (48.5) 541 (47.0) 560 (50.7)
Current residence    
   1-4 years 437 (40.3) 492 (42.7) 472 (42.8)
   5-9 years 257 (23.7) 288 (25.0) 296 (26.8)
   ≥ 10 years 391 (36.0) 372(32.3) 336 (30.4)
Work exposure    
   No 996 (91.8) 1053 (91.4) 999 (90.5)
   Yes 89 (8.2) 99 (8.6) 105 (9.5)
Chronic disease    
   No 825 (76.0) 858 (74.5) 844 (76.4)
   Yes 260 (24.0) 294 (25.5) 260 (23.6)
Previous preterm delivery    
   No 1069 (98.5) 1123 (97.5) 1087 (98.5)
   Yes 16 (1.5) 29 (2.5) 17 (1.5)
Socio economic status    
   Low income 335 (30.9) 337 (29.3) 338 (30.6)
   Medium income 582 (53.6) 642 (55.7) 600 (54.3)
   High income 168 (15.5) 173 (15.0) 166 (15.0)
Body mass index (kg/m2)    
   <25 Normal 618 (57.0) 677 (58.8) 679 (61.5)
   25-30 Overweight 329 (30.3) 334 (29.0) 284 (25.7)
   30 Obesity 138 (12.7) 141 (12.2) 141 (12.8)
Water filter    
   Yes 341 (31.4) 336 (29.2) 338 (30.6)
   No 744 (68.6) 816 (70.8) 766 (69.4)
LBWa    
   Yes 40 (3.7) 51 (4.4) 65 (5.9)
   No 1045 (96.2) 1101 (95.7) 1039 (94.1)
SGA    
   Yes 76 (7.0) 92 (8.0) 102 (9.2)
   No 1009 (93.0) 1060 (92.0) 1002 (90.8)
Mean birth weight (SDs) 3449 (517) 3462 (524) 3430 (559)
  1. ap < 0.05.