Ureaplasma urealyticum and Clinical Outcomes in Extremely Premature Infants: A Single-Center Retrospective Analysis

Background Ureaplasma urealyticum (Uu) colonization is associated with an increased risk of preterm birth. However, whether postnatal Uu colonization in extremely preterm infants affects clinical outcomes—particularly bronchopulmonary dysplasia (BPD)-remains inconsistent in current evidence, with limited domestic research available. Methods This retrospective study included extremely preterm infants admitted to the neonatal intensive care unit between January 2019 and June 2023, who underwent Uu culture via pharyngeal swab within 6 hours after birth (within 2 hours after admission). Infants were divided into Uu-positive and Uu-negative groups based on culture results. Perinatal data and clinical outcomes were collected, and multiple regression analysis was performed to examine the independent association between Uu positivity and BPD, as well as other major outcomes. Results A total of 70 extremely preterm infants were included, of whom 46 (65.7%) required oxygen supplementation at a postmenstrual age of 36 weeks, meeting the diagnostic criteria for BPD. The proportion of infants delivered vaginally was significantly higher in the Uu-positive group than in the Uu-negative group (91.18% vs. 61.11%, P = 0.003). The duration of invasive mechanical ventilation was longer in the Uu-positive group (P = 0.002). Linear regression indicated that both gestational age at birth and Uu positivity significantly influenced the duration of invasive ventilation. However, after adjusting for confounders such as gestational age, birth weight, and mode of delivery in multiple regression analysis, postnatal Uu positivity via pharyngeal swab was not identified as an independent risk factor for BPD. Conclusion Vaginal delivery may increase the risk of postnatal Uu colonization in the respiratory tract of extremely preterm infants. Uu colonization is associated with a longer duration of invasive mechanical ventilation, but this study did not confirm it as an independent risk factor for BPD. Future studies with larger sample sizes and prospective designs are needed to further clarify the role of Uu in lung development in extremely preterm infants.