Catch-Up Growth in Former Preterm Neonates: No Time to Waste

Irrespective of presence of growth restriction at birth, preterm infants are vulnerable to extra-uterine growth restriction (EUGR) during neonatal stay and after discharge, related to cumulative protein and energy deficits. The nutritional management of preterm neonates—including very low birth weight (<1500 g) or extremely low birth weight (<1000 g) infants—aims to result in growth patterns that approximate the intra-uterine fetal growth patterns [1]. If we apply these fetal reference values as a paradigm, a very relevant portion of these preterm patients still develop EUGR during their stay at the neonatal intensive care unit (NICU) [2]. This has clinical relevance, since EUGR and the associated caloric and protein deficits not only result in slower growth velocity, but also are associated with major neonatal morbidities, including bronchopulmonary dysplasia, retinopathy of prematurity and impaired neurodevelopment [1,3]. Along the same line, epidemiologic studies have described additional long-term health consequences of growth restriction and low birth weight, such as an increased risk of cardiovascular (hypertension, microvasculopathy), renal (acute or chronic renal impairment) and metabolic morbidities (insulin resistance, liver steatosis) in adult life, covered in the concept of developmental origins of health and disease (DOHaD) [4]. In term growth-restricted neonates, accelerated weight gain improves weight and length. However, when occurring after the first 2 years of life, this is in itself also linked to a higher incidence of cardiovascular diseases in adulthood [5]. Literature suggests that early catch-up growth (i.e., in the first two years of life) is likely beneficial with regard to renal and general health, whereas delayed catch-up growth (i.e., after two years of age) might be harmful [3]