Longitudinal Assessment of Relationships Between Health Behaviors and IL-6 in Overweight and Obese Pregnancy

Background: Inflammation is a common factor in adverse pregnancy outcomes (APOs). Behavioral factors influence inflammatory markers and APOs but rarely have been investigated simultaneously in pregnancy. Our purpose was to determine how diet, physical activity, and obesity are associated with interleukin (IL)-6 in early and late pregnancy. Methods: We conducted a secondary analysis of 49 overweight/obese pregnant women. Health behavior data, including diet quality using the Dietary Inflammatory Index (DII®); physical activity (Leisure Time Physical Activity scale); body mass index (BMI); and plasma IL-6 concentrations were collected at 13–16 weeks (early pregnancy) and 34–36 weeks (late pregnancy) gestation. Multiple linear regression analyses were used to determine the amount of variance explained in early and late pregnancy IL-6 concentrations by early and late pregnancy diet, physical activity, and BMI. Results: Early diet and early BMI were the strongest predictors of early IL-6 concentrations (R2 = 0.43; p < .001) and late IL-6 concentrations (R2 = 0.30; p < .001). Late BMI predicted late IL-6 (R2 = .11; p = .02). Change in diet over pregnancy predicted late IL-6 (R2 = 0.17; p = .03). Conclusion: These findings suggest that maternal diet and BMI in early pregnancy, which likely reflects prepregnancy status, may have a greater impact on inflammatory processes than factors later in pregnancy. Future work should assess if behavioral factors before pregnancy produce similar relationships to those reported here, which may clarify the timing and type of lifestyle interventions to effectively reduce APOs.