Severity of bronchopulmonary dysplasia and characteristics of neuro-motor development prior to acquisition of independent walking in very preterm and/or very low-birth-weight infants: A retrospective cohort study in a children's medical centre in Japan

Objective: This study aimed to determine the effect of bronchopulmonary dysplasia (BPD) and its severity on neurological examination at equivalent to full term and the development of gross motor skills prior to the acquisition of independent walking in very preterm and/or very low-birth-weight (VLBW) infants.

Methods: This study was a retrospective cohort study. Participants were very preterm and/or VLBW infants who were admitted to a neonatal intensive care unit at a children's hospital in Japan between 2017 and 2021. Clinical, demographic, and outcome variables were retrospectively extracted from medical records. The main outcome measures were the Hammersmith Neonatal Neurological Examination (HNNE) score, a neurological examination at the equivalent of full term, and the age at acquisition of each gross motor skill.

Results: In total, 123 infants were included, of whom 62 did not have BPD, 23 had mild BPD, 25 had moderate BPD, and 13 had severe BPD. No significant differences were observed between groups in the neurological examination results for either the total or categorical HNNE scores. For gross motor skills, the results of hierarchical multiple regression analyses adjusted for confounding factors showed that severe BPD remained a factor that delayed the acquisition of most gross motor milestones, even after changing the models. The unstandardised coefficients (beta) restored to the exponent ranged from 1.16 to 1.32 for all models.

Conclusions: Clinicians involved in the follow-up of very preterm and/or VLBW infants should monitor and support the development of infants with severe BPD from the early postnatal period.