Recent studies have suggested a relationship between maternal Campylobacter rectus infections and preterm low birth weight. The purpose of this study was to investigate the effect of female sex hormones, estradiol and progesterone, on C. rectus and human gingival fibroblasts (HGF). The growth of C. rectus was significantly enhanced by incorporating either estradiol or progesterone in the culture medium. The production of vascular endothelial growth factor (VEGF), interleukin (IL)-6 and IL-8 by HGF increased following stimulation with estradiol or progesterone, at concentrations comparable to those present in the plasma of pregnant women. In addition, a significantly higher secretion of VEGF by HGF treated with the combination of C. rectus and estradiol was observed in comparison with a treatment with C. rectus alone. Stimulation of HGF with VEGF resulted in production of IL-6 and IL-8 in a dose-dependent manner. The capacity of female sex hormones to enhance both C. rectus growth and VEGF, IL-6, and IL-8 production by HGF has the potential to contribute to periodontal disease progression during pregnancy.