STUDY QUESTIONDo any proteomic biomarkers previously identified for pre-eclampsia (PE) overlap with those identified in women with polycystic ovary syndrome (PCOS).SUMMARY ANSWERFive previously identified proteomic biomarkers were found to be common in women with PE and PCOS when compared with controls.WHAT IS KNOWN ALREADYVarious studies have indicated an association between PCOS and PE; however, the pathophysiological mechanisms supporting this association are not known.STUDY DESIGN, SIZE, DURATIONA systematic review and update of our PCOS proteomic biomarker database was performed, along with a parallel review of PE biomarkers. The study included papers from 1980 to December 2013.PARTICIPANTS/MATERIALS, SETTING, METHODSIn all the studies analysed, there were a total of 1423 patients and controls. The number of proteomic biomarkers that were catalogued for PE was 192.MAIN RESULTS AND THE ROLE OF CHANCEFive proteomic biomarkers were shown to be differentially expressed in women with PE and PCOS when compared with controls: transferrin, fibrinogen α, β and γ chain variants, kininogen-1, annexin 2 and peroxiredoxin 2. In PE, the biomarkers were identified in serum, plasma and placenta and in PCOS, the biomarkers were identified in serum, follicular fluid, and ovarian and omental biopsies.LIMITATIONS, REASONS FOR CAUTIONThe techniques employed to detect proteomics have limited ability in identifying proteins that are of low abundance, some of which may have a diagnostic potential. The sample sizes and number of biomarkers identified from these studies do not exclude the risk of false positives, a limitation of all biomarker studies. The biomarkers common to PE and PCOS were identified from proteomic analyses of different tissues.WIDER IMPLICATIONS OF THE FINDINGSThis data amalgamation of the proteomic studies in PE and in PCOS, for the first time, discovered a panel of five biomarkers for PE which are common to women with PCOS, including transferrin, fibrinogen α, β and γ chain variants, kininogen-1, annexin 2 and peroxiredoxin 2. If validated, these biomarkers could provide a useful framework for the knowledge infrastructure in this area. To accomplish this goal, a well co-ordinated multidisciplinary collaboration of clinicians, basic scientists and mathematicians is vital.STUDY FUNDING/COMPETING INTEREST(S)No financial support was obtained for this project. There are no conflicts of interest.