ABSTRACT
OBJECTIVE: To investigate the association between change in body mass index (BMI) from birth to 36 weeks gestation (ΔBMI) and bronchopulmonary dysplasia (BPD) among infants born <30 weeks gestation. METHODS: This was a multicenter retrospective cohort study (2015-2018) of infants born <30 weeks gestation and alive at ≥34 weeks corrected. Main exposure was a change in BMI z score from birth to 36 weeks corrected age grouped into quartiles of change. Association between ΔBMI z scores and BPD was assessed using generalized linear mixed models. RESULTS: Among 772 included infants, 51% developed BPD. From birth to 36 weeks CGA, the weight z score of infants with BPD decreased less than for BPD-free infants, despite a greater decrease in length z score and similar caloric intake resulting in increases in BMI z score (median [IQR], 0.16 [-0.64; 1.03] vs -0.29 [-1.03; 0.49]; P < 0.01). In the adjusted analysis, higher ΔBMI z score quartiles were associated with higher odds of BPD (Q3 vs Q2, AOR [95% CI], 2.02 [1.23; 3.31] and Q4 vs Q2, AOR [95% CI], 2.00 [1.20; 3.34]). CONCLUSION: Among preterm infants, an increase in BMI z score from birth to 36 weeks corrected is associated with higher odds of BPD. IMPACT: Preterm infants with evolving lung disease often experience disproportionate growth in the neonatal period. In this multicenter cohort study, increases in BMI z score from birth to 36 weeks CGA were associated with higher odds of BPD. Despite similar caloric intake, infants with BPD had a higher weight- but lower length-for-age, resulting in higher BMI z score compared to BPD-free infants. This suggests that infants with evolving BPD may require different growth and nutritional targets compared to BPD-free infants.