Aims: To screen the preeclampsia-related protein by proteomics. Methods: Proteomics was performed to identify differential protein expression profiles between normal full-term pregnancy, early-onset severe preeclampsia (ES-PE) or late-onset severe preeclampsia (LS-PE; n = 10 per group). Real-time quantitative PCR and immunohistochemistry were conducted to confirm the expression of α1-antitrypsin (α1-AT) in the decidual tissues of different subjects. ELISA was employed to detect the α1-AT content in the peripheral blood of 90 women (n = 30 per group). Results: We successfully constructed two-dimensional electrophoresis maps of decidual tissues, and a total of 20 differentially expressed proteins were identified. The α1-AT expression was different among the three groups. The normal full-term pregnancy women expressed the most α1-AT, and the LS-PE women expressed the least amount of α1-AT. The difference in the α1-AT expression was consistent with the proteomics data. The peripheral α1-AT content was the highest in the normal full-term pregnancy group (1.85 ± 0.15 g/l), moderate in the ES-PE group (0.77 ± 0.14 g/l) and lowest in the LS-PE group (0.42 ± 0.07 g/l; p < 0.05). Conclusion: Using 2D PAGE, we identified twenty proteins with significantly altered expression in PE. These differentially expressed proteins include prevention protein, in which α1-AT is downregulated in PE. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]