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 5 Associations between maternal BaP-DNA adducts and risk of PB stratified by mean levels of dietary vitamins, folate, and carotene during different pregnancy windows with additional adjustment for supplementation

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
	OR^a	95%CI	OR^a	95%CI	OR^a	95%CI	OR^a	95%CI	OR^a	95%CI	OR^a	95%CI
Vitamin C
Per interquartile increase	1.32	0.88, 1.98	1.46	0.84, 2.55	1.31	0.87, 1.98	1.38	0.82, 2.34	1.52	0.92, 2.52	1.34	0.86, 2.10
> 3.21 compared to ≤ 3.21	2.35	0.90, 6.13	2.44	0.73, 8.20	2.28	0.88, 5.90	2.13	0.68, 6.65	5.21	1.38, 19.75	1.99	0.76, 5.23
Vitamin A
Per interquartile increase	1.13	0.74, 1.73	1.40	0.84, 2.34	1.18	0.76, 1.81	1.45	0.87, 2.39	1.24	0.80, 1.92	1.23	0.74, 2.06
> 3.21 compared to ≤ 3.21	2.11	0.78, 5.73	2.12	0.70, 6.39	2.12	0.77, 5.85	2.63	0.89, 7.71	2.72	0.97, 7.62	1.58	0.49, 5.11
Vitamin E
Per interquartile increase	1.36	0.94, 1.97	1.51	0.78, 2.91	1.45	1.00, 2.10	1.34	0.71, 2.55	1.59	1.03, 2.46	1.55	0.87, 2.77
> 3.21 compared to ≤ 3.21	2.97	1.27, 6.94	1.38	0.32, 5.92	3.07	1.31, 7.23	1.19	0.29, 4.97	4.92	1.73, 14.01	1.47	0.44, 4.88
Folate
Per interquartile increase	1.52	1.00, 2.30	1.66	0.86, 3.18	1.66	1.09, 2.53	1.41	0.75, 2.63	1.37	0.92, 2.06	1.67	0.97, 3.63
> 3.21 compared to ≤ 3.21	3.36	1.32, 8.57	1.79	0.45, 7.20	3.71	1.45, 9.50	1.35	0.34, 5.34	2.70	1.10, 6.62	3.17	0.72, 14.02
Carotene
Per interquartile increase	1.16	0.77, 1.76	1.36	0.80, 2.32	1.20	0.79, 1.83	1.37	0.81, 2.31	1.21	0.79, 1.86	1.25	0.74, 2.10
> 3.21 compared to ≤ 3.21	1.99	0.77, 5.15	2.10	0.63, 7.05	2.27	0.86, 6.06	2.12	0.68, 6.59	2.34	0.87, 6.29	1.60	0.47, 5.46

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

ISSN: 1476-069X