The Incidence of Pulmonary Hypertension and the Association with Bronchopulmonary Dysplasia in Preterm Infants of Extremely Low Gestational Age: Single Centre Study at the Maternity Hospital of University Medical Centre Ljubljana, Slovenia

<b>Background</b>: Pulmonary hypertension (PH) occurs in ~25% of infants with moderate-to-severe bronchopulmonary dysplasia (BPD) and is associated with substantial morbidity and mortality. The American Heart Association and American Thoracic Society recommend routine echocardiographic screening for PH in preterm infants with BPD at 36 weeks' postmenstrual age (PMA), yet the true incidence remains unclear owing to non-uniform diagnostic criteria. Emerging evidence suggests a potential role for earlier screening. <b>Objectives</b>: (i) to determine the incidence of pulmonary hypertension (PH) and bronchopulmonary dysplasia (BPD) in preterm infants of extremely low gestational age; (ii) to determine the incidence of PH among infants diagnosed with BPD (BPD-PH); and (iii) to evaluate the utility of early screening at 7 days of life and late screening at discharge in relation to subsequent BPD. <b>Methods</b>: We conducted a prospective cohort study of all infants born at 22 + 0 to 28 + 6 weeks' gestation and admitted to our tertiary NICU between 1 September 2022 and 31 December 2024. Clinical and echocardiographic assessments for PH and BPD were performed by neonatologists trained in neonatal echocardiography. <b>Results</b>: Seventy-eight infants born at 22 + 0-28 + 6 weeks' gestation were enrolled; 71 underwent early screening and 57 underwent late screening. Early echocardiography at day 7 and late screening at discharge identified no cases of PH. PH was diagnosed clinically and/or echocardiographically in 10 infants before day 7 and in one infant at 38 weeks' PMA. BPD developed in 42 of 57 infants (73.7%). <b>Conclusions</b>: In this cohort of extremely low-gestational-age infants, echocardiographic screening performed by neonatologists detected no PH at day 7 and only one case at late screening (at 38 weeks' PMA/before discharge). Most PH was identified prior to day 7 on clinical and/or echocardiographic grounds.