Ureaplasma urealyticum and clinical outcomes in extremely premature infants: a single-center retrospective exploratory analysis

Ureaplasma urealyticum (Uu) colonization is associated with an increased risk of preterm birth. However, evidence remains inconsistent regarding whether early postnatal Uu positivity affects clinical outcomes in extremely preterm infants, particularly bronchopulmonary dysplasia (BPD), and relevant domestic data are scarce. This retrospective exploratory study included extremely preterm infants admitted to the neonatal intensive care unit between January 2019 and June 2023, from whom pharyngeal swabs were obtained for Uu culture within 6 h after birth. Infants were divided into Uu-positive and Uu-negative groups based on culture results. Perinatal data and clinical outcomes were collected. Multivariable regression analysis was performed to assess the independent association between Uu positivity and BPD, as well as other major morbidities. A total of 70 extremely preterm infants were included, of whom 47 (67.1%) met the diagnostic criteria for BPD. In the comparative analysis of respiratory outcomes, the Uu-positive group exhibited significantly longer duration of invasive ventilation ( P = 0.002) and a higher incidence of BPD (grade ≥ 2) ( P = 0.008); however, after FDR-BH correction, neither difference remained statistically significant (adjusted P = 0.05 and 0.075, respectively). After adjusting for confounders including gestational age, birth weight, and mode of delivery, multivariable regression analysis revealed no statistically significant association between postnatal Uu positivity and BPD in this cohort. Vaginal delivery may increase the risk of postnatal respiratory Uu colonization in extremely preterm infants. Multivariable analysis showed no significant independent association between Uu positivity and BPD, which may be attributable to limited statistical power and residual confounding. Future large-scale prospective studies are warranted to further elucidate the role of Uu in lung development in this vulnerable population.