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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