. Author manuscript; available in PMC: 2016 Jan 31.

Published in final edited form as: Am J Obstet Gynecol. 2014 Aug 8;212(2):208.e1–208.e8. doi: 10.1016/j.ajog.2014.08.007

Table 2.

Odds ratios (95% confidence intervals) for preterm birth in association with interquartile range increase in geometric average (visits 1–3) urinary oxidative stress biomarkers.

Overall preterm birth

Model 1^a				Model 2^b

Biomarker	N (cases, controls)	OR (95% CI)	p	N (cases, controls)	OR (95% CI)	p

8-OHdG	129, 349	0.19 (0.11, 0.34)	<0.001	126, 331	0.19 (0.10, 0.34)	<0.001
8-Isoprostane	129, 349	2.17 (1.48, 3.20)	<0.001	126, 331	2.22 (1.47, 3.36)	<0.001

Spontaneous preterm birth

Model 1^a				Model 2^b

Biomarker	N (cases, controls)	OR (95% CI)	p	N (cases, controls)	OR (95% CI)	p value

8-OHdG	56, 349	0.21 (0.10, 0.42)	<0.001	56, 331	0.18 (0.09, 0.40)	<0.001
8-Isoprostane	56, 349	4.25 (2.21, 8.15)	<0.001	56, 331	6.25 (2.86, 13.7)	<0.001

Placental preterm birth

Model 1^a				Model 2^b

Biomarker	N (cases, controls)	OR (95% CI)	p	N (cases, controls)	OR (95% CI)	p value

8-OHdG	35, 349	0.17 (0.07, 0.41)	<0.001	33, 331	0.11 (0.04, 0.32)	<0.001
8-Isoprostane	35, 349	1.45 (0.79, 2.66)	0.24	33, 331	0.94 (0.52, 1.70)	0.84

Abbreviations: 8-OHdG, 8-hydroxydeoxyguanosine; OR, odds ratio.

Model 1 adjusted for urinary specific gravity only.

Model 2 adjusted for urinary specific gravity, maternal age, race/ethnicity, education level, health insurance provider, and pre-pregnancy body mass index (BMI).