The impact of prematurity on postnatal growth of different renal compartments

In humans, nephrogenesis ceases before birth but the renal medulla compartment continues to develop after birth. We aim to evaluate the relative growth of different renal compartments in preterm babies compared to age-matched term babies, and explore the impact of premature birth on postnatal renal maturation, remodelling, and possible long-term implications.This retrospective study compared the renal ultrasonographic images between preterm babies and term infants. Ultrasound images were obtained at 32 weeks (preterm), 37 weeks and at six months of age. Kidney volume, length, renal cortex and medulla thickness were measured and compared between preterm and term babies.Preterm babies were lighter in body weight and shorter for crown-heel length at age-matched 37 weeks. All kidney growth parameters were also smaller compared to term babies. However, by six months of age kidney volume and length measurements were no longer significantly different between the two groups though preterm babies were still significantly lighter and shorter. The catch-up of the overall kidney growth in preterm babies was mainly attributed to the hypertrophic growth of the renal cortex while the postnatal renal medulla growth was disrupted. This trend continued as the renal cortical thickness became significantly larger while the medulla became smaller in preterm babies at six months of age, compared to age-matched term baby.In preterm babies the renal cortical region undergoes accelerated growth after birth while the renal medulla growth lags behind. Further investigations will be necessary to determine whether this has a negative impact on renal function later in life. This article is protected by copyright. All rights reserved