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Table 1 Characteristics of mother–child pairs, according to urinary cotinine in pregnancy, healthy start (2010–2014)

From: Prenatal exposure to tobacco and adverse birth outcomes: effect modification by folate intake during pregnancy

 

Preterm & SGA Births a,b

Neonatal Adiposity f,g

Cotinine Categories h

Cotinine Categories h

 

 < 0.05

0.05–550

 ≥ 550

  

 < 0.05

0.05–550

 ≥ 550

 

Total (n = 701)

No exposure (n = 516, 73.6%)

Secondhand Smoke (n = 143, 20.4%)

Active Smoker (n = 42, 6.0%)

p-value e

Total (n = 630)

No exposure (n = 463, 73.5%)

Secondhand Smoke (n = 132, 21.0%)

Active Smoker (n = 35, 5.5%)

p-valuee

Maternal characteristics c

 Maternal age (yrs)

29 ± 6

30 ± 5

24 ± 6

27 ± 5

p < 0.01

28.9 ± 6

30 ± 5

24 ± 6

27 ± 5

p < 0.01

 Pre-pregnancy BMI (kg/m2)

25 ± 6

25 ± 5

26 ± 7

26 ± 7

p = 0.06

25.5 ± 6

25 ± 6

26 ± 6

26 ± 7

p = 0.10

 Gravidity, number of pregnancies

1 ± 1

1 ± 1

1 ± 1

2 ± 2

p < 0.01

1 ± 1

1 ± 1

1 ± 1

2 ± 2

p < 0.01

Maternal race/ethnicity

 non-Hispanic white

399 (57%)

337 (65%)

44 (31%)

18 (43%)

p < 0.01

354 (56%)

298 (64%)

42 (32%)

14 (40%)

p < 0.01

 non-Hispanic black

84 (12%)

24 (5%)

46 (32%)

14 (33%)

75 (12%)

22 (5%)

41 (31%)

12 (34%)

 Hispanic

174 (25%)

128 (25%)

39 (27%)

7 (17%)

162 (26%)

119 (26%)

37 (28%)

6 (17%)

 Other

44 (6%)

27 (5%)

14 (10%)

3 (7%)

39 (6%)

24 (5%)

12 (9%)

3 (9%)

Household income

 < 40,000

179 (25%)

97 (19%)

60 (42%)

22 (52%)

p < 0.01

165 (26%)

90 (19%)

58 (44%)

17 (49%)

p < 0.01

 40,001–70,000

134 (19%)

105 (20%)

19 (13%)

10 (24%)

120 (19%)

94 (20%)

17 (13%)

9 (26%)

 > 70,000

264 (38%)

247 (48%)

14 (10%)

3 (7%)

234 (37%)

220 (48%)

11 (8%)

3 (9%)

 Don't know

124 (18%)

67 (13%)

50 (35%)

7 (17%)

111 (18%)

59 (13%)

46 (35%)

6 (17%)

Mother's highest level of education

 < 12 years

87 (12%)

39 (8%)

38 (27%)

10 (24%)

p < 0.01

81 (13%)

36 (8%)

36 (27%)

9 (26%)

p < 0.01

 High School Degree

111 (16%)

58 (11%)

43 (30%)

10 (24%)

101 (16%)

52 (11%)

41 (31%)

8 (23%)

 College classes or college degree

503 (72%)

419 (81%)

62 (43%)

22 (52%)

448 (71%)

375 (81%)

55 (42%)

18 (51%)

 Maternal Average Daily Total Caloric Intake Throughout Pregnancy (kcal)

2055 ± 686

2005 ± 552

2176 ± 950

2249 ± 978

p < 0.01

2046 ± 675

1996 ± 546

2186 ± 944

2183 ± 896

p < 0.01

 Healthy Eating Index d

62 ± 11

64 ± 10

56 ± 10

52 ± 9

p < 0.01

62 ± 11

64 ± 10

56 ± 10

52 ± 10

p < 0.01

Healthy Eating Index (≥ , < median value. 61) d

 ≥ median value

365 (52%)

316 (61%)

40 (28%)

9 (21%)

p < 0.01

327 (52%)

283 (61%)

36 (27%)

8 (23%)

p < 0.01

 < median value

309 (44%)

186 (36%)

92 (64%)

31 (74%)

278 (44%)

167 (36%)

86 (65%)

25 (71%)

 missing

27 (4%)

14 (3%)

11 (8%)

2 (5%)

25 (4%)

13 (3%)

10 (8%)

2 (6%)

 Total Folic Acid Supplementation & Dietary Folate Equivalents d

1385 ± 544

1418 ± 552

1292 ± 508

1294 ± 520

p = 0.03

1384 ± 533

1418 ± 543

1312 ± 509

1216 ± 438

p = 0.02

Total Folic Acid Supplementation & Dietary Folate Equivalents d

 ≥ 1077 µg/day

520 (74%)

400 (77%)

96 (67%)

24 (57%)

p < 0.01

470 (75%)

361 (78%)

91 (69%)

18 (51%)

p < 0.01

 < 1077 µg/day

177 (25%)

113 (22%)

46 (32%)

18 (43%)

156 (24%)

99 (21%)

40 (30%)

17 (49%)

 missing

4 (1%)

3 (1%)

1 (1%)

0 (0%)

4 (1%)

3 (1%)

1 (1%)

0 (0%)

Offspring characteristics

Infant Sex

 Female

337 (48%)

246 (48%)

73 (51%)

18 (43%)

p = 0.61

309 (49%)

227 (49%)

68 (52%)

14 (40%)

p = 0.48

 Male

362 (52%)

268 (52%)

70 (49%)

24 (57%)

321 (51%)

236 (51%)

64 (48%)

21 (60%)

 Missing

2 (0.3%)

2 (0.4%)

0 (0%)

0 (0%)

0 (0%)

0 (0%)

0 (0%)

0 (0%)

  1. Note: Continuous variables shown as mean ± standard deviations; categorical variables displayed as proportions of column totals
  2. SGA small-for-gestational age {based on sex, race/ethnic and parity specific growth curves
  3. a Preterm births defined as those not completing 37 weeks gestation
  4. b 20 infants missing gestational age measurements excluded
  5. c All maternal characteristics, unless otherwise noted, were measured at 17 week pregnancy visit
  6. d Dietary characteristics collected using the automated self-administered 24-h dietary recall (ASA24) at minimum twice over the course of the pregnancy (range: 2–8 times); 25 percentile cut-point (1077mcg/day) used for categorical folate analyses
  7. e One-way analysis by variance (ANOVA) tests used to examine differences in means across the urinary cotinine categories. Chi-square square tests used to examine proportion differences across urinary cotinine categories
  8. f Neonatal adiposity (fat mass percentage) is calculated as a proportion of fat mass/total body mass (collected within 72 h following delivery using the BOD POD)
  9. g 91 infants missing neonatal adiposity measurements excluded
  10. h Contine levels expressed in nanograms/milliliter (ng/ml); limit of detection (LOD) =  ~ 0.05 ng/ml