title: Association between zinc level and the risk of preeclampsia: a meta-analysis.
abstract: BACKGROUND
  Epidemiological studies evaluating the association between zinc level and the risk of preeclampsia have produced inconsistent results. We therefore conducted a meta-analysis to summarize the evidence for them.
  
  
  METHODS
  Pertinent studies were identified by a search in PubMed and Web of Knowledge up to April 2015. Standardized mean difference (SMD) was performed to combine the results. Random-effect model was used. Publication bias was estimated using Egger's regression asymmetry test.
  
  
  RESULTS
  Thirteen articles (11 case-control studies and 2 cross-sectional studies) involving 445 preeclampsia cases and 568 healthy controls were included in this meta-analysis. Our pooled results suggested that preeclampsia patients had a lower zinc level as compared with healthy, pregnant controls (summary SMD = -0.61, 95 % CI = -0.74, -0.48, I (2) = 88.5 %). The association was also significant in Asia (SMD = -0.73, 95 % CI = -0.88, -0.58), but not in Europe. No publication biases were found.
  
  
  CONCLUSIONS
  Our analysis indicated that zinc level in preeclampsia patients was significantly lower than that of healthy, pregnant women, especially among the Asian population.
authors.affiliation: Department of Prenatal Diagnosis Center, Nantong Maternity and Child Health Hospital, Nantong, Jiangsu, 226006, People's Republic of China.
authors.forename: Qingwen
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Prenatal Diagnosis Center, Nantong Maternity and Child Health Hospital, Nantong, Jiangsu, 226006, People's Republic of China.
authors.forename: Lingli
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Prenatal Diagnosis Center, Nantong Maternity and Child Health Hospital, Nantong, Jiangsu, 226006, People's Republic of China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Prenatal Diagnosis Center, Nantong Maternity and Child Health Hospital, Nantong, Jiangsu, 226006, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Prenatal Diagnosis Center, Nantong Maternity and Child Health Hospital, Nantong, Jiangsu, 226006, People's Republic of China.
authors.forename: Jiangyue
authors.initials: J
authors.lastname: Liu
authors.affiliation: President's Office, Nantong Maternity and Child Health Hospital, No. 399, Century Avenue, Nantong, Jiangsu, 226006, People's Republic of China. jianhuachen888@163.com.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Chen
mesh_terms: D005260:Female; D006801:Humans; D011225:Pre-Eclampsia / Q000453:epidemiology* / Q000517:prevention & control; D011247:Pregnancy; D012307:Risk Factors; D015032:Zinc / Q000097:blood*
chemical_list: D015032:Zinc
keywords: Meta-analysis; Preeclampsia; Zinc level