Table 4.

Hazard ratios (HR) of preeclampsia and 95% confidence intervals (CIs) in association with an interquartile range difference in oxidative stress biomarker.

	Average of visits 1–3		Visit 1		Visit 2		Visit 3		Visit 4
Model 1	HR (95% CI)	p	HR (95% CI)	p	HR (95% CI)	p	HR (95% CI)	p	HR (95% CI)	p
8-OHdG	0.84 (0.64, 1.09)	0.19	1.03 (0.83, 1.27)	0.81	0.88 (0.71, 1.10)	0.26	0.73 (0.59, 0.91)	0.01	0.80 (0.61, 1.04)	0.09
8-iso	1.62 (1.22, 2.15)	<0.01	1.69 (1.27, 2.25)	<0.01	1.57 (1.20, 2.05)	<0.01	1.09 (0.87, 1.38)	0.44	1.19 (0.90, 1.57)	0.23
Model 2
8-OHdG	0.46 (0.32, 0.65)	<0.01	0.44 (0.32, 0.61)	<0.01	0.34 (0.23, 0.51)	<0.01	0.54 (0.36, 0.81)	<0.01	0.64 (0.41, 1.00)	0.05
8-iso	1.89 (1.27, 2.81)	<0.01	1.55 (1.06, 2.25)	0.02	1.91 (1.28, 2.86)	<0.01	1.49 (1.06, 2.11)	0.02	1.64 (1.07, 2.52)	0.02
Model 3
8-OHdG	0.47 (0.33, 0.66)	<0.01	0.40 (0.28, 0.56)	<0.01	0.32 (0.21, 0.49)	<0.01	0.53 (0.35, 0.81)	<0.01	0.59 (0.37, 0.95)	0.03
8-iso	1.52 (1.04, 2.23)	0.03	1.35 (0.96, 1.91)	0.09	1.68 (1.14, 2.48)	0.01	1.23 (0.89, 1.69)	0.22	1.57 (1.04, 2.35)	0.03

Model 1 unadjusted for covariates. Model 2 adjusted for specific gravity (average or visit specific) only. Model 3 adjusted for specific gravity (average or visit specific) as well as maternal race/ethnicity and body mass index at visit 1. Sample sizes for Model 1 and Model 2 (preeclamptic and normotensive pregnancies) for 8-OHdG: Average (50, 391); Visit 1 (50, 381); Visit 2 (43, 341); Visit 3 (44, 327), Visit 4 (30, 312); and for 8-iso: Average (50, 391); Visit 1 (50, 383); Visit 2 (43, 341); Visit 3 (44, 328); Visit 4 (30, 312). Sample sizes for Model 3 (preeclamptic and normotensive pregnancies for 8-OHdG: Average (50, 388); Visit 1 (50, 378); Visit 2 (43, 340); Visit 3 (44, 326); Visit 4 (30, 309); and for 8-iso: Average (50, 388); Visit 1 (50, 380); Visit 2 (43, 340); Visit 3 (44, 327); Visit 4 (30, 309).