Table 2.

Unadjusted and Adjusted Associations Between Physical Activity During Pregnancy and Preterm Delivery in Total Cohort: Baltimore Preterm Delivery Study (2001–2004)

Physical Activity Type	Unadjusted		Adjusted
	PR	95% CI	PR	95% CI
Any LTPA*
No (Referent)
Yes	0.80	0.57, 1.11	0.86	0.61, 1.23
LTPA (min/wk)†
0 (Referent)
1–60	0.79	0.54, 1.16	0.91	0.61, 1.36
>60	0.80	0.48, 1.35	0.77	0.44, 1.36
Intensity of LTPA‡
None (Referent)
Light/moderate	0.89	0.63, 1.25	1.01	0.71, 1.44
High	0.48	0.20, 1.12	0.35	0.11, 1.01
Stair climbing (times/d)§
≤10 (Referent)
>10	0.93	0.67, 1.29	0.82	0.57, 1.16
Walking for a purpose (min/d)||
≤30 (Referent)
>30	0.70	0.49, 1.01	0.64	0.43, 0.94

Abbreviations: LTPA, leisure time physical activity; PR, prevalence ratio.

^*Adjusted for drug use, cigarette smoking (2nd trimester), locus of control, family resource scale.

^†Adjusted for locus of control, family resource scale.

^‡Adjusted for locus of control, family resource scale, cigarette smoking, drug use, depression.

^§Adjusted for locus of control, family resource scale, cigarette smoking, drug use.

^||Adjusted for drug use, locus of control, family resource scale.