Increased serum iron levels in pregnant women with preeclampsia: a meta-analysis of observational studies

Our study aimed to investigate whether the serum iron levels in patients with preeclampsia were higher than in healthy pregnant women and to evaluate potential heterogeneities. We searched Pubmed, Embase, Web of Science and Medline databases for studies before September 2016. The standardised mean difference (SMD) and 95% confidence interval (CI) were used to combine results across the studies, in addition to the random-effect model. A total of 10 studies involving 363 patients with preeclampsia and 370 healthy controls were eligible through the inclusion criteria. In comparison with healthy pregnant women, the serum iron levels are higher in the patients with preeclampsia [summary SMD = 0.28, 95% CI = 0.11-0.44], and this association was also significant in the case-control studies. The serum iron levels were higher in the pregnant women with preeclampsia than in the healthy controls in both the Asian and European populations. Our study provides significant evidence of higher serum iron levels in the patients with preeclampsia than in healthy pregnant women. Impact Statement What is already known on this subject? Serum iron levels have inconsistent associations with a risk of preeclampsia in pregnant women. What the results of this study add? Compared with healthy pregnant women, serum iron levels are higher in patients with preeclampsia. What the implications are of these findings for clinical practice and/or further research? Further studies across large numbers of cases and increased patient populations are necessary to confirm our findings.