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Table 2 Characteristics of the study cohorts - potential confounding factors

From: Association of maternal serum concentrations of 2,2', 4,4'5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE) levels with birth weight, gestational age and preterm births in Inuit and European populations

  

Greenland

Kharkiv

Warsaw

Age [years]

 

26.8 (± 6.1)

6.1 (± 25)

25 (± 4.8)

Pre-pregnancy BMI [kg/m2]

 

24.5 (± 4.3)

4.3 (± 21.6)

21.6 (± 3.2)

Education

left before 15 or 15-17

227 (41.5%)

156 (27%)

-

 

left at age 18

46 (8.4%)

144 (25%)

44 (22.2%)

 

continued above age 18

211 (38.6%)

207 (35.9%)

150 (75.8%)

 

missing

63 (11.5%)

70 (12.1%)

4 (2.0%)

Marital status

married

114 (20.8%)

322 (55.8%)

160 (80.8%)

 

living as married

323 (59.0%)

195 (33.8%)

32 (16.2%)

 

living alone

55 (10.1%)

51 (8.8%)

6 (3.0%)

 

missing

55 (10.1%)

9 (1.6%)

0 (0.0%)

Smoking1

never smoker

64 (11.7%)

368 (63.8%)

129 (65.2%)

 

smoker

65 (11.9%)

78 (13.5%)

32 (16.2%)

 

ex-smoker

418 (76.4%)

131 (22.7%)

37 (18.7%)

Exposure to other people's cigarette smoke1

no

146 (26.7%)

110 (19.1%)

71 (35.9%)

 

yes

390 (71.3%)

455 (78.9%)

126 (63.6%)

 

missing

11 (2.0%)

12 (2.1%)

1 (0.5%)

Alcohol

drinks1

less than 14/week

519 (94.9%)

576 (99.8%)

197 (99.5%)

 

14 and more/week

28 (5.1%)

1 (0.2%)

1 (0.5%)

Occupational

exposure1

no

539 (98.5%)

497 (86.1%)

172 (86.9%)

 

yes

8 (1.5%)

80 (13.9%)

26 (13.1%)

Previous pregnancies

0

63 (11.5%)

320 (55.5%)

148 (74.7%)

 

1

83 (15.2%)

127 (22.0%)

34 (17.2%)

 

2+

395 (72.2%)

107 (18.5%)

9 (4.5%)

 

missing

6 (1.1%)

23 (4.0%)

7 (3.5%)

Newborn sex

Boy

295 (53.9%)

300 (52.0%)

96 (48.5%)

 

Girl

292 (53.4%)

277 (48.0%)

102 (51.5%)

  1. 1during the period of attempt to conceive