SFTPD and bronchopulmonary dysplasia: Bronchoalveolar lavage (BAL) samples taken from preterm infants over the first few days after birth have demonstrated low concentrations of SP-D in association with respiratory distress syndrome (RDS) that were associated with an increased risk of BPD.22 23 Binding assay studies evaluating the lectin activity of SP-D demonstrate that the SP-D present in the BAL of preterm infants was less effective than that in term infants.23