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Table 3 Characteristics of the study population (N = 396,049) according to the categories of exposure, Taiwan, 2001–2003.

From: Water disinfection by-products and the risk of specific birth defects: a population-based cross-sectional study in Taiwan

Characteristic

TTHMs (0–4 μg/L) Reference N (%)

TTHMs (5–9 μg/L) Low N (%)

TTHMs (10–19 μg/L) Medium N (%)

TTHMs (20+ μg/L) High N (%)

Total N (%)

Total

181,985 (100%)

55,950 (100%)

82,797 (100%)

75,317 (100%)

396,049 (100%)

Gender of infant

     

   Male

95,027 (52.2%)

29,128 (52.1%)

43,155 (52.1%)

39,413 (52.3%)

206,723(52.2%)

   Female

86,958 (47.8%)

26,822 (47.9%)

39,642 (47.9%)

35,904 (47.7%)

189,326 (47.8%)

Maternal age

     

   <20 years

6,419 (3.5%)

1,838 (3.3%)

3,499 (4.2%)

3,461 (4.6%)

15,217 (3.8%)

   20–34

156,087 (85.8%)

46,871 (83.8%)

72,402 (87.4%)

65,947 (87.6%)

341,307 (86.2%)

   35-

19,476 (10.7%)

7,241 (12.9%)

6,893 (8.3%)

5,909 (7.8%)

39,519 (10.0%)

Maternal diabetes mellitus

     

   Yes

418 (0.2%)

189 (0.3%)

179 (0.2%)

144 (0.2%)

930 (0.2%)

   No

181,567 (99.8%)

55,761 (99.7%)

82,618 (99.8%)

75,173 (99.8%)

395,119 (99.8%)

Plurality

     

   Singleton

176,791 (97.1%)

54,383 (97.2%)

80,755 (97.5%)

73,442 (97.5%)

385,371 (97.3%)

   Multiple birth

5,194 (2.9%)

1,567 (2.8 %)

2,042 (2.5%)

1,875 (2.5%)

10,678 (2.7%)

Population density (no of people/km2)*

     

   <1000

29,881 (16.4%)

6,697 (12.0%)

20,387 (24.6%)

26,392 (35.2%)

83,357 (21.1%)

   1000–5000

71,005 (39.0%)

27,257 (48.7%)

23,569 (28.5%)

31,823 (42.5%)

153,654 (38.8%)

   >5000

81,099 (44.6%)

21,996 (39.3%)

38,841 (46.9%)

16,738 (22.3%)

158,674 (40.1%)