INTRODUCTION: Current Neonatology has failed to reduce the incidence of moderate-severe bronchopulmonary dysplasia (BPD). Although multiple models for predicting the risk of dysplasia in preterm infants have been studied, none have been implemented in clinical practice.

OBJECTIVE: To calculate a mathematical model to predict moderate-severe bronchopulmonary dysplasia in newborns before 30 weeks of gestation based on pre and postnatal clinical variables, lung ultrasound images and detection of biomarkers in nasopharyngeal aspirate.

METHODOLOGY: Multicenter case-control study, in which 10 Spanish neonatal intensive care units (NICU) will participate. All participants will undergo a lung ultrasound in the first 24 hours, on the third day of life, at one week and two weeks of life, a nasopharyngeal aspirate at one week of life, and cardiac ultrasound at one week and two weeks of life. It is expected to include 240 patients in 29 months of study among all participating units: 200 for the calculation of the model, and 40 more for its subsequent validation. These will be divided between those with a diagnosis of moderate-severe BPD and those without, and the values of each of the variables described in the methodology section will be compared between the two groups. Those with a significant difference will be entered into a logistic regression model to calculate those that best predict the final diagnosis. With the results of the calculated model, a mobile application will be created with a risk of moderate-severe BPD calculator in this population, for its worldwide distribution.

Type of study: case-control study. Study population: Neonates of less than 30 weeks´ gestation, born at any of the study centers, or transferred from other centers in the first 24 hours of life, during the study period. The participating hospitals will be: Puerta del Mar University Hospital in Cádiz, Basurto University Hospital in Bilbao, Álvaro Cunqueiro University Hospital in Vigo, Doctor Josep Trueta University Hospital in Girona, Clínic University Hospital in Barcelona, León University Hospital, Gregorio Marañón University Hospital in Madrid, German Trias i Pujol Hospital in Barcelona, Miguel Servet Hospital in Zaragoza and Val d'Hebron Hospital in Barcelona.

Study protocol: The following lung ultrasounds will be performed on the patients included in the study: first 24 hours of life, 3rd day of life (DOL) and 7th DOL. At one week of life detection of proteins in nasopharyngeal aspirates will be performed. During the first week of life, an echocardiography will be performed in all patients to evaluate the possibility of a patent ductus arteriosus and its hemodynamic significance.

In the first 20 patients who remain intubated at one week of life, tracheal aspirates will be obtained too, to compare protein determination

Inclusion Criteria:

• Neonates of less than 30 weeks´ gestation, born at any of the study centers, or transferred from other centers in the first 24 hours of life, during the study period

Exclusion Criteria:

• Neonates with severe chromosomal abnormalities, or severe congenital anomalies, infants who died prior to 36 weeks´ corrected age, as well as patients whose clinical condition prevents the performance of the study protocol ultrasounds.

Neonates born before 30 weeks' gestation.