Physical activity, sedentary behavior, and C-reactive protein in pregnancy

Elevated C-reactive protein (CRP) is associated with adverse pregnancy outcomes. In nonpregnant populations, physical activity has been inversely associated with CRP, but this association has not been evaluated during pregnancy. The purpose of this study was to evaluate the association between objectively measured physical activity, sedentary behavior, and CRP by pregnancy trimester.

We evaluated this association among 294 pregnant participants in the National Health and Nutrition Examination Survey (2003-2004 and 2005-2006). Physical activity (min·d(-1)) was assessed via accelerometer using established cut points. CRP (mg·L(-1)) was measured using a high sensitivity assay. Multivariable linear regression was used to determine the relationship between physical activity, sedentary behavior, and CRP by trimester of pregnancy.

Among women in the second trimester, after adjusting for age, body mass index, smoking status, and history of adverse pregnancy outcomes, light-intensity physical activity was associated with lower CRP (β = -0.002, P = 0.05). In unadjusted models, sedentary time and proportion of wear time spent sedentary were positively associated with CRP (β = 0.048, P = 0.02 and β = 2.36, P = 0.03, respectively); however, the relationship was no longer statistically significant in multivariable models (β = 0.33, P = 0.2 and β = 1.96, P = 0.08, respectively). Neither physical activity nor sedentary behavior was associated with CRP among women in the first or third trimester.

Objectively measured light-intensity physical activity had a protective effect on CRP among women in the second trimester of pregnancy. Findings highlight the need for longitudinal studies of pregnancy physical activity and CRP with careful control for clinical characteristics of the current pregnancy.