Inflammation and Triglycerides Partially Mediate the Effect of Prepregnancy Body Mass Index on the Risk of Preeclampsia

• Published in: American journal of epidemiology 2005-12, Vol.162 (12), p.1198-1206
• Main Authors: Bodnar, Lisa M., Ness, Roberta B., Harger, Gail F., Roberts, James M.
• Format: Article
• Language: English
• Subjects: adjusted odds ratio; Adult; Analysis. Health state; AOR; Biological and medical sciences; BMI; Body Mass Index; C-reactive protein; C-Reactive Protein - metabolism; Case-Control Studies; Cholesterol; Confounding Factors, Epidemiologic; CRP; Diseases of mother, fetus and pregnancy; Epidemiology; Female; General aspects; Gynecology. Andrology. Obstetrics; Humans; Hypertension; inflammation; Inflammation - blood; Inflammatory diseases; Logistic Models; Medical sciences; Metabolic diseases; Obesity; Obesity - blood; Obesity - epidemiology; Pennsylvania - epidemiology; pre-eclampsia; Pre-Eclampsia - blood; Pre-Eclampsia - epidemiology; Pregnancy; Pregnancy. Fetus. Placenta; Prospective Studies; Proteins; Public health. Hygiene; Public health. Hygiene-occupational medicine; Risk Assessment; Risk Factors; triglycerides; Triglycerides - blood
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/aje/kwi334

The objective of this study was to quantify the mediating role of inflammation and triglycerides in the association between prepregnancy body mass index (weight (kg)/height (m)2) and preeclampsia. The authors conducted a nested case-control study of 55 preeclamptic women and 165 pregnant controls from the Pregnancy Exposures and Preeclampsia Prevention Study (Pittsburgh, Pennsylvania, 1997–2001). Serum samples collected at ≤20 weeks' gestation were analyzed for levels of C-reactive protein and triglycerides. The adjusted odds ratio (AOR) from a multivariable conditional logistic regression model assessing the total effect of body mass index on preeclampsia risk was compared with the AOR from the same model after results were controlled for C-reactive protein, triglycerides, and confounding factors (direct-effects model). The percentage of the total effect that was mediated through inflammation and triglycerides was calculated as 100 − [ln(direct-effects AOR)/ln(total-effects AOR)]. In the total-effects model, 4- and 8-unit increases in body mass index were associated with 1.7-fold (95% confidence interval (CI): 1.3, 2.3) and 2.9-fold (95% CI: 1.6, 5.2) increases in preeclampsia risk, whereas in the direct-effects model, these AORs were 1.4 (95% CI: 1.0, 1.9) and 2.0 (95% CI: 1.0, 3.8), respectively. Inflammation was a more important mediator than triglycerides. These findings suggest that approximately one third of the total effect of body mass index on preeclampsia risk is mediated through inflammation and triglyceride levels.