Table 2

Crude and adjusted relative risks (RRs) of congenital anomalies related to exposure to bromodichloromethane (BDCM) and chloroform during pregnancy

Defects and anomalies Cases
(births) n2-150 		Rate/1000 Crude RR
(95% CI) 		Adjusted RR
(95% CI)
Neural tube defects:
 BDCM (μg/l):
  <5 35  (26636)1.31.01.02-151
  5–9 27 (13837)2.01.5 (0.9 to 2.5)1.4 (0.8 to 2.3)2-151
  10–195 (5638)0.90.7 (0.3 to 1.7)0.6 (0.2 to 1.5)2-151
  ⩾20 10 (2734)3.72.8 (1.4 to 5.6)2.5 (1.2 to 5.1)2-151
 Chloroform(μg/l):
  <5033 (18964)1.71.01.02-151
  50–7419 (16323)1.20.7 (0.4 to 1.2)0.7 (0.4 to 1.2)2-151
  75–998 (6685)1.20.7 (0.3 to 1.5)0.7 (0.3 to 1.5)2-151
  ⩾10017 (6873)2.51.4 (0.8 to 2.6)1.2 (0.7 to 2.3)2-151
Cardiovascular anomalies:
 BDCM (μg/l):
  <5258 (26977)9.61.01.02-151
  5–9125 (13653)9.21.0 (0.8 to 1.2)1.0 (0.8 to 1.2)2-151
  10–1939 (5546)7.00.7 (0.5 to 1.0)0.7 (0.5 to 1.0)2-151
  ⩾208 (2669)3.00.3 (0.2 to 0.6)0.3 (0.2 to 0.7)2-151
 Chloroform (μg/l):
  <50170 (19057)8.91.01.02-151
  50–74153 (16350)9.41.0 (0.8 to 1.3)1.0 (0.8 to 1.3)2-151
  75–9960 (6550)9.21.0 (0.8 to 1.4)1.0 (0.8 to 1.4)2-151
  ⩾10047 (6888)6.80.8 (0.6 to 1.1)0.7 (0.5 to 1.0)2-151
Cleft defects:
 BDCM (μg/l):
  <550 (27426)1.81.01.02-152
  5–917 (13972)1.20.7 (0.4 to 1.2)0.7 (0.4 to 1.2)2-152
  10–1912 (5723)2.11.2 (0.6 to 2.2)1.1 (0.6 to 2.1)2-152
  ⩾203 (2721)1.10.6 (0.2 to 1.9)0.6 (0.2 to 1.9)2-152
 Chloroform (μg/l):
  <5028 (19351)1.41.01.02-152
  50–7429 (16597)1.71.2 (0.7 to 2.0)1.2 (0.7 to 2.0)2-152
  75–999 (6696)1.30.9 (0.4 to 2.0)0.9 (0.4 to 2.0)2-152
  ⩾10016 (7198)2.21.5 (0.8 to 2.8)1.5 (0.8 to 2.8)2-152
Chromosomal abnormalities:
 BDCM (μg/l):
  <554 (26214)2.11.01.02-151
  5–929 (14565)2.01.0 (0.6 to 1.5)1.0 (0.6 to 1.5)2-151
  10–198 (5304)1.50.7 (0.3 to 1.5)0.7 (0.4 to 1.6)2-151
  ⩾205 (2762)1.80.9 (0.4 to 2.2)0.9 (0.4 to 2.3)2-151
 Chloroform (μg/l):
  <5030 (19416)1.51.01.02-151
  50–7433 (16086)2.11.3 (0.8 to 2.2)1.3 (0.8 to 2.2)2-151
  75–9919 (6721)2.81.8 (1.0 to 3.3)1.9 (1.1 to 3.3)2-151
  ⩾10014 (6622)2.11.4 (0.7 to 2.6)1.4 (0.8 to 2.8)2-151

  • ↵2-150 Subjects with missing values for adjustment variables were excluded.

  • ↵2-151 Adjusted for maternal age and income level.

  • ↵2-152 Adjusted for maternal age.