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Table 1 Characteristics of NTD cases and controls in phase 2 for methylation assay

From: Aberrant methylation of Pax3 gene and neural tube defects in association with exposure to polycyclic aromatic hydrocarbons

Characteristic

Control (N = 29)a

Case (N = 73)a

P valueb

Maternal age (years)

0.703

 < 25

14 (50.0)

30 (41.1)

 25–29

6 (21.4)

20 (27.4)

 ≥ 30

8 (28.6)

23 (31.5)

BMI (kg/m2)

0.595

 < 18.5

2 (6.9)

6 (8.6)

 18.5–27.9

22 (75.9)

57 (81.4)

 ≥ 28

5 (17.2)

7 (10.0)

Maternal education

0.005

 Primary or lower

4 (13.8)

9 (12.5)

 Junior high

12 (41.4)

52 (72.2)

 High school or above

13 (44.8)

11 (15.3)

Occupation

< 0.001

 Farmer

14 (48.3)

61 (87.1)

 Non-farmer

15 (51.7)

9 (12.9)

Previous birth defects history

0.200

 Yes

0

4 (5.6)

 No

28 (100)

67 (94.4)

Gravidity

0.219

 1

17 (58.6)

32 (45.1)

 ≥ 2

12 (41.4)

39 (54.9)

Parity

0.060

 1

18 (72.0)

32 (50.0)

 ≥ 2

7 (28.0)

32 (50.0)

Periconceptional folic acid supplementation

< 0.001

 Yes

4 (14.3)

42 (60.0)

 No

24 (85.7)

28 (40.0)

Cold or fever

0.059

 Yes

5 (17.9)

27 (37.5)

 No

23 (82.1)

45 (62.5)

Active or passive smoking

0.210

 Yes

15 (55.6)

29 (41.4)

 No

12 (44.4)

41 (58.6)

Drinking

0.940

 Yes

17 (65.4)

47 (66.2)

 No

9 (34.6)

24 (33.8)

Gestational age (weeks)

0.023

 < 28

14 (48.3)

52 (72.2)

 28–36

7 (24.1)

14 (19.4)

 > 36

8 (27.6)

6 (8.3)

Fetal sex

0.129

 Male

17 (58.6)

28 (41.8)

 Female

12 (41.4)

39 (58.2)

  1. aData were presented in number (percentage). Total number may not be equal to the total of cases or controls due to missing or unknown data
  2. bCases and controls were compared by Pearson’s χ2 test, or Fisher’s exact test if any cell expectation was less than 5