Periodontitis associated with Porphyromonas gingivalis infection is a risk factor for infertility through uterine hypertrophy

Periodontitis has recently been recognized as a potential risk factor for infertility due to its adverse effect on conception, although the underlying mechanisms remain unclear. This study investigated serum IgG antibody titers against periodontopathogenic bacteria in women with unexplained infertility and investigated how periodontal inflammation affects pregnancy and uterine function using a ligature-induced periodontitis mouse model infected with Porphyromonas gingivalis (Pg). IgG antibody titers against seven periodontopathogenic bacteria strains were measured by ELISA in 76 spontaneously pregnant women and 70 women undergoing infertility treatment. In the in vivo study, periodontitis mice were bred four weeks after periodontitis induction. Birth numbers, newborn weights, and gestation periods were assessed. To evaluate periodontal inflammation, alveolar bone, serum, and uterus was collected before mating. Uterine tissue was evaluated through histological and immunohistochemical staining. Women receiving infertility treatment were significantly older and had higher IgG titers against three Pg strains. Periodontitis mice had fewer births, lower newborn weights, and increased uterine cross-sectional areas. Additionally, elevated estrogen receptor α and progesterone receptor expression levels were observed in endometrial and stromal tissues. These results suggest that periodontitis may cause uterine hypertrophy and hormone receptor changes, potentially impairing pregnancy.