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Table 2 Maternal characteristics associated with dietary nitrite intake, National Birth Defects Prevention Study Controls, 1997-2004

From: Maternal characteristics associated with the dietary intake of nitrates, nitrites, and nitrosamines in women of child-bearing age: a cross-sectional study

 

Nitrite intake (mg/day)

 

Odds ratios and 95% confidence intervalsb

 

Quartile 1a

Quartile 2

Quartile 3

Quartile 4

   
 

0.10123 - 1.12224

1.12225 - 1.53386

1.53386 - 2.1305

>2.1305

p-value

4th quartile compared to the 1st quartile

 

n

%

n

%

n

%

n

%

 

Crude

Adjustedb

Race/Ethnicity

           

   White non-Hispanic

1044

29.9

1016

29.1

889

25.4

548

15.7

<0.0001

1.0

1.0

   Black non-Hispanic

155

23.5

138

20.9

182

27.6

185

28.0

 

2.3 (1.8,2.9)

1.9 (1.3,2.7)

   Hispanic

166

12.8

214

16.5

305

23.6

610

47.1

 

7.0 (5.7,8.6)

6.2 (4.3,9.0)

   Asian/Pacific Islander

33

19.5

42

24.9

36

21.3

58

34.3

 

3.3 (2.2,5.2)

10.3 (5.4,19.6)

   Other

45

25.6

40

22.9

40

22.9

50

28.6

 

2.1 (1.4,3.2)

2.2 (1.2,4.2)

   Missing

12

54.5

4

18.3

3

13.6

3

13.6

 

---

---

State/Area of residence

           

   Texas

106

15.4

128

18.7

171

24.9

282

41.0

<0.0001

1.0

1.0

   Arkansas

145

20.5

152

21.5

196

27.6

215

30.4

 

0.56 (0.41,0.76)

0.88 (0.55,1.4)

   California

149

19.1

145

18.5

199

25.4

289

37.0

 

0.73 (0.54,0.98)

0.49 (0.32,0.76)

   Georgia

165

27.0

155

25.3

153

25.0

139

22.7

 

0.28 (0.20,0.38)

0.67 (0.42,1.1)

   Iowa

184

28.5

155

24.0

171

26.4

136

21.1

 

0.11 (0.08,0.16)

0.30 (0.18,0.50)

   Massachusetts

234

31.5

264

35.6

175

23.6

69

9.3

 

0.31 (0.23,0.43)

0.50 (0.30,0.82)

   New Jersey

156

27.6

145

25.6

135

23.8

130

23.0

 

0.22 (0.16,0.3)

0.51 (0.31,0.86)

   New York

161

30.7

143

27.2

125

23.8

96

18.3

 

0.32 (0.23,0.43)

0.54 (0.33,0.89)

   North Carolina

74

25.3

87

29.8

73

25.0

58

19.9

 

0.29 (0.20,0.44)

0.45 (0.24,0.82)

   Utah

81

31.4

80

31.0

57

22.1

40

15.5

 

0.19 (0.12,0.29)

0.22 (0.12,0.41)

Dietary folate equivalent (μg/day)

           

   <319

670

27.7

398

27.6

267

18.5

105

7.3

<0.0001

1.0

1.0

   319-464.9

369

25.2

440

30.0

410

28.0

246

16.8

 

4.3 (3.3,5.5)

1.9 (1.3,2.6)

   465 - 685.5

267

18.2

374

25.5

430

29.4

394

26.9

 

9.4 (7.3,12.2)

1.8 (1.3,2.6)

   > 685.5

149

10.3

242

16.7

348

24.0

709

49.0

 

30.4 (23.2,39.8)

2.3 (1.5,3.3)

Maternal household income (dollars annually)

           

   ≥50,000

559

30.5

582

31.7

452

24.6

243

13.2

<0.0001

1.0

1.0

   40-49,999

117

27.7

119

28.1

106

25.1

81

19.1

 

1.6 (1.2,2.2)

1.0 (0.66,1.6)

   30-39,999

138

25.5

130

24.0

143

26.4

131

24.1

 

2.2 (1.6,2.9)

1.4 (0.92,2.0)

   20-29,999

168

22.6

178

23.9

188

25.2

211

28.3

 

2.9 (2.2,3.7)

1.2 (0.81,1.7)

   10-19.999

132

18.3

133

18.4

192

26.5

266

36.8

 

4.6 (3.6,6.0)

1.0 (0.68,1.5)

   < 10,000

196

21.1

166

17.8

201

21.6

368

39.5

 

4.3 (3.4,5.4)

0.71 (0.48,1.1)

   Missing

145

23.5

146

23.6

173

28.0

154

24.9

 

---

---

Maternal education (years at school)

           

   16+

538

29.4

585

32.0

456

24.9

251

13.7

<0.0001

1.0

1.0

   13-15

374

24.3

388

25.2

428

27.8

352

22.7

 

2.0 (1.6,2.5)

1.3 (0.98,1.8)

   12

356

24.7

316

21.9

332

23.0

438

30.4

 

2.6 (2.1,3.2)

1.2 (0.88,1.7)

   9-11

145

20.8

112

16.1

171

24.5

269

38.6

 

4.0 (3.1,5.1)

1.2 (0.79,1.9)

   0-8

31

11.2

47

17.0

63

22.7

136

49.1

 

9.4 (6.2,14.3)

2.9 (1.4,5.8)

   Missing

11

36.7

6

20.0

5

16.7

8

26.7

 

---

---

Dietary Fat (% of daily calories)

           

   ≤ 30%

950

29.4

827

25.6

756

23.4

702

21.6

<0.0001

1.0

1.0

   >30%

505

19.6

627

24.2

699

27.1

752

29.1

 

2.0 (1.7,2.3)

8.7 (6.9,11.0)

Pre-pregnancy BMI

           

   Normal weight (18.5 < 25.0)

882

28.1

820

26.1

734

23.4

705

22.4

<0.0001

1.0

---

   Under weight (<18.5)

80

25.4

74

23.5

80

25.4

81

25.7

 

1.3 (0.92,1.8)

---

   Over weight (25.0 < 30.0)

286

23.0

320

25.7

332

26.7

307

24.6

 

1.3 (1.1,1.6)

---

   Obese (≥30.0)

184

20.7

198

22.3

257

28.9

249

28.1

 

1.7 (1.4,2.1)

---

   Missing

23

10.0

42

18.3

52

22.8

112

48.9

 

---

---

Folic acid containing supplements

           

   No

600

23.1

558

21.4

646

24.8

799

30.7

<0.0001

1.0

---

   Yes

846

26.6

888

27.9

799

25.1

650

20.4

 

0.57 (0.50,0.67)

---

   Missing

9

28.1

8

25.0

10

31.3

5

15.6

 

---

---

Multivitamin use

           

   No

891

25.0

951

26.6

898

25.2

829

23.2

<0.0001

1.0

---

   Yes

556

25.0

502

22.6

552

24.8

613

27.6

 

1.2 (1.0,1.4)

---

   Missing

8

30.8

1

3.8

5

19.2

12

46.2

 

---

---

Age at conception (years)

           

   20-24

325

24.2

307

22.9

323

24.1

386

28.8

<0.0001

1.0

 

   <20

204

24.7

165

20.0

185

22.3

273

33.0

 

1.1 (0.89,1.4)

---

   25-29

379

24.3

409

26.2

391

25.0

382

24.5

 

0.85 (0.69,1.0)

---

   30-34

372

26.1

383

26.8

382

26.7

291

20.4

 

0.66 (0.53,0.81)

---

   35+

175

26.5

190

28.7

174

26.3

122

18.5

 

0.59 (0.44,0.77)

---

  1. aReferent category is nitrite intake at the lowest quartile of intake (<1.2225 mg.day)
  2. bOnly presented for variables included in the final multinomial logistic regression model
  3. cAdjusted for tertiles of daily caloric intake, race/ethnicity, state of residence, maternal education, dietary fat intake, maternal household income, and dietary folate as dietary folate equivalents
  4. Note: p-value excludes missing values
  5. Note: missing categories contain refuse, don't know, and missing
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