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Table 3 Maternal characteristics associated with total dietary nitritea 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

 

Total Nitrite intake (mg/day)

 

Odds ratios and 95% confidence intervalsc

 

Quartile 1b

Quartile 2

Quartile 3

Quartile 4

   
 

0.31362-2.63578

2.63579 - 3.69108

3.69109 - 5.21853

5.21854 - 59.0717

p-value

4th quartile compared to the 1st quartile

 

n

%

n

%

n

%

n

%

 

Crude

Adjustedd

Race/Ethnicity

           

   White non-Hispanic

1024

29.3

988

28.3

903

25.9

577

16.5

<0.0001

1.0

1.0

   Black non-Hispanic

132

20

134

20.4

151

22.9

242

36.7

 

3.3 (2.6,4.1)

2.6 (1.8,3.6)

   Hispanic

222

17.2

263

20.3

315

24.3

494

38.2

 

3.9 (3.3,4.8)

2.0 (1.5,2.8)

   Asian/Pacific Islander

28

16.7

19

11.3

39

23.2

82

48.8

 

5.2 (3.3, 8.1)

9.2 (5.1,16.7)

   Other

39

22.3

42

24

43

24.6

51

29.1

 

2.3 (1.5,3.6)

1.9 (1.1,3.5)

   Missing

8

38.1

6

28.6

1

4.7

6

28.6

 

---

---

State/Area of residence

           

   Texas

140

20.4

171

24.8

166

24.2

210

30.6

<0.0001

1.0

1.0

   Arkansas

178

25.2

181

25.7

163

23.1

183

26

 

0.69 (0.51,0.93)

0.76 (0.50,1.2)

   California

176

22.6

162

20.8

188

24.1

253

32.5

 

0.96 (0.72,1.3)

0.84 (0.57,1.2)

   Georgia

137

22.5

135

22.1

159

26.1

179

29.3

 

0.24 (0.18,0.34)

0.40 (0.25,0.63)

   Iowa

229

35.4

178

27.6

155

24.0

84

13

 

0.54 (0.40,0.74)

1.7 (1.1,2.7)

   Massachusetts

173

23.3

213

28.7

215

29.0

141

19

 

0.97 (0.70,1.3)

1.7 (1.1,2.6)

   New Jersey

114

20.1

141

24.9

145

25.7

166

29.3

 

0.51 (0.37,0.71)

1.0 (0.65,1.6)

   New York

147

28.1

125

23.8

139

26.5

113

21.6

 

0.87 (0.64,1.2)

1.5 (0.93,2.3)

   North Carolina

76

26

73

25

66

22.6

77

26.4

 

0.68 (0.46,0.99)

1.3 (0.76,2.2)

   Utah

83

32.2

73

28.3

56

21.7

46

17.8

 

0.37 (0.24,0.56)

0.51 (0.29,0.90)

Dietary folate equivalent (μg/day)

           

   <319

739

51.4

427

29.6

208

14.5

64

4.5

<0.0001

1.0

1.0

   319-464.9

349

23.9

463

31.6

441

30.1

210

14.4

 

6.9 (5.1,9.4)

4.0 (2.9,5.7)

   465-685.5

232

15.9

352

24.1

452

30.9

426

29.1

 

21.2 (15.7,28.7)

6.4 (4.5,9.1)

   >685.5

133

9.2

210

14.5

351

24.3

752

52

 

65.3 (47.6,89.5)

8.7 (6.0,12.6)

Folic acid containing supplements

           

   No

646

24.9

606

23.3

625

24.0

722

27.8

<0.0001

1.0

1.0

   Yes

799

25.1

837

26.3

820

25.8

722

22.7

 

0.81 (0.70,0.94)

1.1 (0.89,1.3)

   Missing

8

25

9

28.1

7

21.9

8

25

 

---

---

Maternal education (years at school)

           

   16+

473

25.9

517

28.3

458

25.0

381

20.8

<0.0001

1.0

1.0

   12-15

390

25.3

393

25.5

400

26.0

357

23.2

 

1.1 (093,1.4)

0.80 (0.61,1.0)

   12

377

26.2

346

24.1

349

24.3

366

25.5

 

1.2 (0.99,1.5)

0.55 (0.42,0.73)

   9-11

164

23.5

142

20.4

163

23.4

228

32.7

 

1.7 (1.4,2.2)

0.49 (0.34,0.70)

   0-8

42

15.2

46

16.7

74

26.8

114

41.3

 

3.4 (2.3,4.9)

0.87 (0.46,1.7)

   Missing

7

24.1

8

27.6

8

27.6

6

20.7

 

---

---

Dietary Fat (% of daily calories)

           

   < 30%

844

26.1

773

23.9

786

24.4

825

25.6

0.0280

1.0

1.0

   >30%

609

23.6

679

26.3

666

25.8

627

24.3

 

1.1 (0.91,1.2)

2.5 (2.0,3.0)

Pre-pregnancy BMI

           

   Normal weight (18.5 < 25.0)

843

26.9

772

24.6

772

24.6

749

23.9

0.1870

1.0

1.0

   Under weight (<18.5)

72

22.9

80

25.5

78

24.8

84

26.8

 

1.3 (0.94,1.8)

1.1 (0.73,1.7)

   Over weight (25.0 < 30.0)

301

24.2

327

26.2

323

26.0

293

23.6

 

1.1 (0.91,1.3)

1.3 (0.80,2.0)

   Obese (>30.0)

203

22.9

231

26

213

24.0

240

27.1

 

1.3 (1.1,1.6)

1.8 (1.1,2.9)

   Missing

34

14.9

42

18.5

66

28.9

86

37.7

 

---

---

Maternal household income (dollars annually)

           

   ≥50,000

484

26.4

516

28.1

474

25.8

361

19.7

<0.0001

1.0

---

   40-49,999

116

27.4

122

28.8

94

22.3

91

21.5

 

1.1 (0.77,1.4)

---

   30-39,999

150

27.7

125

23.1

148

27.4

118

21.8

 

1.1 (0.80,1.4)

---

   20-29,999

176

23.6

184

24.7

204

27.4

181

24.3

 

1.4 (1.1,1.8)

---

   10-19.999

157

21.7

150

20.9

180

24.9

235

32.5

 

2.0 (1.6,2.6)

---

   < 10,000

211

22.8

189

20.4

207

22.4

319

34.4

 

2.0 (1.6,2.5)

---

   Missing

159

25.8

166

26.9

145

23.5

147

23.8

 

---

---

Multivitamin use

           

   No

882

24.7

914

25.7

905

25.4

863

24.2

0.2470

1.0

---

   Yes

563

25.4

537

24.2

539

24.2

581

26.2

 

1.1 (0.91,12)

---

   Missing

8

32

1

4

8

32.0

8

32

 

---

---

Age at conception

           

   20-24

377

28.2

320

23.9

314

23.4

328

24.5

0.002

1.0

 

   <20

230

27.9

200

24.4

188

22.8

205

24.9

 

1.0 (0.81,1.3)

---

   25-29

389

24.9

385

24.7

386

24.8

400

25.6

 

1.2 (0.96,1.4)

---

   30-34

317

22.2

375

26.3

400

28.1

334

23.4

 

1.2 (0.98,1.5)

---

   35+

140

21.2

172

26

164

24.8

185

28

 

1.5 (1.2,1.9)

---

  1. aTotal dietary nitrite = 5% dietary nitrate + dietary nitrite
  2. bReferent category is total nitrite intake at the lowest quartile of intake (<2.63578 mg/day)
  3. cOnly presented for variables included in the final multinomial logistic regression model
  4. dAdjusted for tertiles of daily caloric intake, race/ethnicity, maternal education, state of residence, dietary fat intake, pre-pregnancy body mass index, and folic acid supplementation
  5. Note: p-value excludes missing values
  6. Note: missing categories contain refuse, don't know, and missing