Table 4.

The association between past week physical activity (using perceived intensity at 17–22 weeks of pregnancy) and umbilical artery resistance index at 24–29 weeks of pregnancy (N = 781).

Modeling with physical activity in perceived intensity*
	Beta (95% CI)	p-value
Total physical activity (median = 2.75 hrs/wk)
No activity†	Reference
Fairly light total activity	0.005 (−0.013, 0.021)	0.62
MV total activity <= the median	0.009 (−0.011, 0.027)	0.39
MV total activity > the median	0.007 (−0.014, 0.019)	0.50
Recreational activity (median = 2.0 hrs/wk)
No recreational activity†	Reference
Fairly light recreational activity	−0.002 (−0.021, 0.009)	0.79
MV recreational activity <= the median	0.002 (−0.016, 0.017)	0.71
MV recreational activity > the median	−0.004 (−0.017, 0.011)	0.58
Work activity
No work activity†	Reference
Fairly light work activity	−0.005 (−0.013, 0.006)	0.43
Some MV work activity	0.001 (−0.010, 0.014)	0.86

CI: confidence interval, MV: moderate to vigorous.

Median among participants who reported at least some moderate to vigorous activities.

^*Adjusted for household percentage of poverty (<100, 100–200, >200), weight gain ratio of observed weight/expected weight based on IOM guidelines (<1, 1–<2, >=2), gestational age at second visit (weeks), placental location at second visit (anterior, posterior, other), and other physical activity.

^† referent group, women with no specific activity.

In all models, variables with more than two levels were coded as indicator variables.