Objectives: This study aims to determine whether high C-reactive protein (CRP) concentration during pregnancy is associated with later preeclampsia and whether weight status (BMI) is a potential modifier of the relation between CRP and preeclampsia.
Methods: Twenty-three studies were included in a systematic literature review and a subset of 18 in a meta-analysis. Weighted mean difference (WMD) [with their 95% confidence intervals (CI)] of CRP in preeclampsia and control groups was the estimator. A quality assessment was carried out using a scale specifically developed for this study. Meta-regression with estimates for study characteristics and inter-arm differences and sensitivity and subgroup analysis was employed. Statistical heterogeneity was investigated using I(2) statistic.
Results: The pooled estimated CRP between 727 women, who developed preeclampsia and 3538 controls was 2.30 mg/l (95% CI: 1.27-3.34). The heterogeneity among studies was high (I(2) = 92.8). The WMD was found to be lower in studies comprising preeclampsia and control groups with similar BMI [WMD = 0.85 (95% CI: 0.10-1.61); I(2) = 25.3%] compared with studies among which BMI was significantly elevated in the preeclampsia group [2.01 (95% CI: 1.23-2.78); I(2) = 0.0%], which may explain the high heterogeneity of pooled data. Meta-regression results confirmed that difference in BMI between groups modifies the association of CRP and preeclampsia. High quality studies represented 30%.
Conclusion: The pooled WMD suggest that women with higher levels of CRP may have an increased risk of developing preeclampsia. This association seems to be modified by confounders, such as BMI. Further studies of high methodological quality are needed.