Neurodevelopmental outcomes of infants with very low birth weights are associated with the severity of their extra-uterine growth retardation

Background: For infants with very low birth weights (VLBW), their neurodevelopmental outcomes are thought to be associated with extra-uterine growth retardation (EUGR). In this study, based on a single institute, we analyzed the association between different levels or severity of EUGR of VLBW infants and their neurodevelopmental outcomes later at a corrected age of 24 months.

Methods: This is a hospital-based retrospective cohort study. The severity of EUGR was classified into three categories according to the z-score of discharge weight: z < -2.0, <-2.5, and <-3.0. The outcomes were assessed using the Bayley Scales of Infant Development-II (BSID-II) at a corrected age of 24 months. We then estimated the association of EUGR with low mental developmental index (MDI) or low psychomotor developmental index (PDI). Multiple logistic regression and stratified analyses were used to adjust for the possible confounding factors.

Results: In total, 224 VLBW infants were enrolled in this study from 1997 to 2006. In the univariate analysis, EUGR for weight at discharge from hospital was associated with MDI <85 at the corrected age of 24 months, and this association was related to the severity of EUGR (z < -2.5, OR: 1.92 (1.04-3.53); z < -3.0, OR: 2.83 (1.26-6.36)). In addition, the relationship was not confounded by gender nor small for gestational age. The stratified analysis against hemodynamic significant patent ductus arteriosus also revealed that EUGR was an independent predictor for neurodevelopmental outcomes.

Conclusion: In VLBW preterm infants, EUGR was significantly associated with low MDI scores assessed at a corrected age of 24 months. Early evaluation and recognition of EUGR should be emphasized when caring for preterm infants.