Objective
To compare the expression of hypoxia inducible factor 1α (HIF1α) and micro-blood vessels in endometrium around the time of embryo implantation in women with recurrent miscarriage and fertile controls. Design: Retrospective study. Setting: University hospitals. Patient(s): Sixty women: 24 with recurrent miscarriage and 36 with proven fertility. Intervention(s): Endometrial biopsy samples obtained precisely 7 days after luteinization hormone (LH) surge in a natural cycle. Main outcome measure(s): Immunohistochemical analysis to determine expression of HIF1α and micro-blood vessels as identified by von Willebrand factor (vWF) in endometrium; semiquantitative analysis using H-score analysis of staining intensity for HIF1α in the luminal epithelium, glandular epithelium, and stroma, separately; number, diameter, and volume of vWF-positive endometrial micro-vessels as counted by Image J software. Result(s): The luminal epithelial and stromal expression of HIF1α in women with recurrent miscarriage was higher than found in the fertile controls, with the change in the luminal epithelium reaching the highest statistical significance. There was no statistically significant difference in HIF1α expression in glandular epithelium between the two groups. An increased number as well as volume of micro-blood vessels was observed in women with recurrent miscarriage although the mean diameter of the micro-blood vessels did not statistically significantly differ between the two groups.