Nonlinear relationship between vitamin D status on admission and bronchopulmonary dysplasia in preterm infants.

Background: This research will explore non-linear relationship between vitamin D status on admission and bronchopulmonary dysplasia (BPD) in preterm infants.

Methods: Data were retrospectively collected on preterm infants ≤32 weeks gestation and ≥28 weeks gestation hospitalized in our hospital between Jan. 2019 and Jul. 2022, which were classified into BPD and non-BPD groups according to BPD diagnostic criteria. Independent influences between the two groups were staged using comparison of differences between groups, univariate analysis, multivariate analysis, smoothed curve fitting, and threshold effect staging.

Results: 255 preterm infants were enrolled in this research, including 135 males and 120 females, with a mean gestational age of 30.59 ± 0.86 weeks. Vitamin D status on admission was an independent protective factor for BPD in preterm infants, with a 6% reduction in the probability of BPD for every 1 ng/ml increase in vitamin D status on admission (p = 0.036). There was also a non-linear relationship, with each 1 ng/ml increase in vitamin D status on admission being associated with an 87% reduction in the incidence of BPD when vitamin D status was <12.82 ng/ml (p = 0.010).

Conclusion: Vitamin D status on admission and BPD are non-linearly in preterm infants at 28-32 weeks gestation.

Impact statement: Analyzing the relationship between vitamin D status on admission and BPD. A nonlinear relationship and turning point between vitamin D status on admission and BPD was derived by curve fitting and threshold effect. We provide a new reference point for vitamin D supplementation for the prevention of neonatal BPD and to avoid ineffective overmedication.