The Relationship between Serum Zinc Level and Preeclampsia: A Meta-Analysis

The association between serum zinc level and preeclampsia (PE) remains controversial. A systematic literature search was performed in PubMed, Web of Science and Embase for relevant available articles. The articles were limited to those in English from January 1990 to April 2015. Observational studies evaluating the association between serum zinc level and PE were included. The I-2 was used to assess heterogeneity and the random effect model (REM) was adopted as the pooling method. The pooled standard mean difference (SMD) with 95% confidence interval (CI) was used to estimate the association between serum zinc level and PE. Seventeen observational studies were included. Compared with healthy pregnancy controls, PE patients have lower serum zinc level in 14 studies about total PE (SMD (95% CI): -0.587 (-0.963, -0.212), Z = 3.06, p for Z = 0.002; I-2 = 88.4%, p for I-2 < 0.0001). In subgroup analysis, a lower serum zinc level in PE patients compared with healthy pregnancy controls was observed in studies conducted in Asia, studies with zinc level measured in serum, and studies involving fasting participants. The SMD did not differ significantly between studies with healthy pregnancy controls matched by individual age (yes or no), and by individual gestational age (yes or no), respectively. Results from this meta-analysis indicate that serum zinc level in PE patients is significantly lower than that in healthy pregnancy controls. A moderate amount of zinc supplementation during pregnancy is advocated to reduce the incidence of PE.