Effect of seminal Ureaplasma urealyticum infection on IVF and ICSI outcomes: increased rescue ICSI and miscarriage rates in IVF cycles

Ureaplasma urealyticum (UU) is a common pathogen that contributes to male infertility; however, its impact on assisted reproductive technology (ART) outcomes remains unclear. This study aimed to investigate the impact of seminal UU infection on sperm quality, embryo quality, and pregnancy outcomes in patients undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). We conducted a retrospective analysis of 2315 couples who underwent their first ART at the Reproductive Medicine Center of our hospital between June 2019 and December 2024. The patients were categorized into four groups based on the insemination method (IVF or ICSI) and seminal UU infection status: IVF-UU (−), IVF-UU ( +), ICSI-UU (−), and ICSI-UU ( +) groups. We assessed the variations in sperm quality, embryo quality, and clinical outcomes between the UU (−) and UU ( +) groups across the different insemination methods. Univariate and multivariate linear/logistic regression models were used to evaluate the impact of UU infection on sperm quality and ART outcomes. UU infection did not significantly affect any sperm parameters in the IVF group (all P > 0.05). In contrast, in the ICSI-UU ( +) group, semen volume and motility after swim-up were significantly reduced compared to the ICSI-UU (−) group (2.50 vs. 2.00, P = 0.016; 73.78 vs. 62.74, P = 0.020). The rescue ICSI and miscarriage rates were significantly higher in the IVF-UU ( +) group than in the IVF-UU (−) group (9.9% vs. 6.3%, P = 0.019; 23.9% vs. 14.4%, P = 0.026). Univariate and multivariate logistic regression analyses demonstrated that UU infection was an independent influencing factor for both rescue ICSI and miscarriage in patients undergoing IVF. No statistically significant differences were identified in other embryo or clinical outcomes between the UU (−) and UU ( +) groups in either the IVF or ICSI cohort (all P > 0.05). UU infection adversely affects the clinical outcomes of IVF patients, acting as an independent factor correlated with increased rates of rescue ICSI and miscarriage. These findings underscore the clinical necessity of screening for and addressing UU infection prior to the initiation of ART to enhance the efficacy of treatment and pregnancy outcomes. Trial registration: Clinical trial registration https://www.medicalresearch.org.cn/login, identifier MR-45-25-074284.