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Table 4 Associations between maternal BaP-DNA adducts and risk of PB stratified by mean levels of dietary vitamins, folate, and carotene during different pregnancy windows

From: Effects of Benzo[a]pyrene-DNA adducts, dietary vitamins, folate, and carotene intakes on preterm birth: a nested case–control study from the birth cohort in China

BaP-DNA adducts (µg/gDNA)

Preconception & During pregnancy

During pregnancy only

Preconception only

 ≤ Mean levels

 > Mean levels

 ≤ Mean levels

 > Mean levels

 ≤ Mean levels

 > Mean levels

ORa

95%CI

ORa

95%CI

ORa

95%CI

ORa

95%CI

ORa

95%CI

ORa

95%CI

Vitamin C

 Per interquartile increase

1.33

0.89, 1.99

1.22

0.82, 1.81

1.36

0.82, 2.27

1.29

0.77, 2.15

1.49

0.90, 2.46

1.32

0.85, 2.05

  > 3.21 compared to ≤ 3.21

2.39

0.93, 6.18

2.14

0.85, 5.40

2.10

0.69, 6.45

2.05

0.68, 6.19

4.83

1.31, 17.80

1.95

0.75, 5.04

Vitamin A

 Per interquartile increase

1.20

0.79, 1.81

1.37

0.83, 2.27

1.25

0.82, 1.90

1.42

0.87, 2.32

1.33

0.87, 2.03

1.21

0.73, 2.01

  > 3.21 compared to ≤ 3.21

2.24

0.85, 5.93

2.06

0.70, 6.12

2.25

0.84, 6.05

2.56

0.89, 7.38

2.94

1.08, 7.98

1.55

0.48, 4.97

Vitamin E

 Per interquartile increase

1.37

0.95, 1.97

1.27

0.69, 2.35

1.46

1.01, 2.12

1.17

0.64, 2.15

1.62

1.05, 2.50

1.36

0.79, 2.32

  > 3.21 compared to ≤ 3.21

2.81

1.27, 6.68

1.09

0.27, 4.33

3.03

1.31, 7.03

0.98

0.25, 3.87

4.88

1.75, 13.65

1.28

0.40, 4.10

Folate

 Per interquartile increase

1.55

1.03, 2.34

1.42

0.78, 2.59

1.69

1.11, 2.57

1.26

0.70, 2.27

1.41

0.95, 2.10

1.67

0.90, 3.09

  > 3.21 compared to ≤ 3.21

3.42

1.37, 8.58

1.54

0.40, 5.94

3.78

1.49, 9.60

1.19

0.31, 4.53

2.79

1.16, 6.72

2.79

0.66, 11.86

Carotene

 Per interquartile increase

1.22

0.82, 1.81

1.35

0.80, 2.27

1.26

0.84, 1.89

1.36

0.82, 2.27

1.30

0.86, 1.98

1.23

0.74, 2.05

  > 3.21 compared to ≤ 3.21

2.14

0.85, 5.40

2.08

0.65, 6.89

2.42

0.94, 6.24

2.10

0.69, 6.45

2.64

1.01, 6.92

1.57

0.47, 5.28

  1. aAdjusted for maternal age, education, family income per month, maternal BMI, passive smoking, parity, C-section, newborn gender, activity, and employment during pregnancy
  2. Abbreviations: PB Preterm birth, BaP Benzo[a]Pyrene, OR Odds Ratio, CI Confidence interval