A multilevel examination of exercise intention and behavior during pregnancy.

Research examining exercising in pregnancy is limited by non-theoretical and cross-sectional assessments that fail to capture the specific physical and psychological demands of the pregnancy trimesters. Drawing on a population in Gainesville, Florida, USA we prospectively examined, within a multilevel design, 61 pregnant women's first and second trimester exercise intention and behavior, and the potential moderating effect of past exercise behavior using the framework of the Theory of Planned Behavior (TPB). Significant cross-sectional associations were found with exercise intention, although the only significant longitudinal effect was the relation between first trimester intention and second trimester changes in exercise behavior. Implications of our findings for study design and exercise intervention development during pregnancy are discussed.