Lifestyle factors have been linked to decreased sperm quality and may influence the prevalence of Ureaplasma urealyticum infection. This study aims to clarify the relationships among Ureaplasma urealyticum infection, lifestyle factors, and semen quality. In this retrospective study, 2668 male partners of infertile couples who underwent fertility evaluation at the Center for Reproduction and Genetics of The First Affiliated Hospital of USTC (Hefei, China) between April 2020 and March 2023 were enrolled. Participants were assessed for semen parameters, clinical characteristics, and lifestyle factors. Of the 2668 participants, 659 (24.7%) participants were positive for Ureaplasma urealyticum. Body mass index (BMI), smoking, and sexual frequency (>2 times per week) were significantly higher in the Ureaplasma urealyticum-positive group than those in the Ureaplasma urealyticum-negative group. After adjustment for potential confounders, smoking (odds ratio [OR] = 1.23, 95% confidence interval [CI]: 1.02–1.49, P = 0.03) and sexual frequency (more than twice per week; OR = 1.41, 95% CI: 1.04–1.91, P = 0.03) remained associated with Ureaplasma urealyticum infection. Regarding semen parameters, ejaculate volume was significantly lower in the Ureaplasma urealyticum-positive group (P = 0.002); however, the prevalence of abnormal semen quality did not differ between the two groups. Logistic regression and restricted cubic spline analysis revealed no significant associations between poor semen quality and Ureaplasma urealyticum infection. In conclusion, Ureaplasma urealyticum infection was associated with certain lifestyle factors but not with semen quality. Further research is required to elucidate the underlying mechanisms and to evaluate potential interventions.

Keywords: lifestyle factors; semen parameters; Ureaplasma urealyticum; smoking; sex frequency