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

Table 3 Associations between maternal BaP-DNA adducts and risk of PB, and between dietary vitamins, folate, carotene intake and risk of PB by different pregnancy windows

Characteristics & time windows	OR^a	95%CI	OR^b	95%CI
Maternal BaP-DNA adducts (µg/gDNA)
Per interquartile increase	1.27	0.95, 1.67	1.28	0.95, 1.72
> 3.21 compared to ≤ 3.21	2.05	1.05, 4.01	2.09	1.06, 4.11
Dietary intake > mean levels compared to ≤ mean levels
Vitamin C (mg)
Preconception & during pregnancy	0.43	0.21, 0.87	0.39	0.19, 0.80
During pregnancy only	0.55	0.27, 1.10	0.48	0.24, 0.99
Preconception only	0.39	0.18, 0.84	0.34	0.16, 0.76
Vitamin A (µg RE)
Preconception & during pregnancy	0.47	0.23, 0.96	0.43	0.21, 0.89
During pregnancy only	0.56	0.28, 1.14	0.52	0.25, 1.07
Preconception only	0.39	0.19, 0.81	0.34	0.16, 0.71
Vitamin E (mg)
Preconception & during pregnancy	0.49	0.23, 1.04	0.45	0.21, 0.97
During pregnancy only	0.57	0.27, 1.19	0.54	0.26, 1.13
Preconception only	0.38	0.19, 0.80	0.35	0.16, 0.73
Folate (µg)
Preconception & during pregnancy	0.32	0.16, 0.67	0.30	0.14, 0.63
During pregnancy only	0.40	0.20, 0.81	0.38	0.19, 0.78
Preconception only	0.38	0.18, 0.79	0.35	0.16, 0.74
Carotene (µg)
Preconception & during pregnancy	0.43	0.21, 0.89	0.37	0.17, 0.78
During pregnancy only	0.50	0.24, 1.01	0.43	0.21, 0.90
Preconception only	0.39	0.19, 0.81	0.33	0.16, 0.71

^aAdjusted for maternal age, education, family income per month, maternal BMI, passive smoking, parity, C-section, newborn gender, activity, and employment during pregnancy
^bAdditional adjusted for supplementation status (ever, never)
Abbreviations: PB Preterm birth, BaP Benzo[a]Pyrene, OR Odds Ratio, CI Confidence interval

ISSN: 1476-069X