Cardiovascular fitness is impaired in children born small for gestational age

Small for gestational age (SGA) refers to a child whose weight and, or, length at birth is less than a 2 standard deviation score (SDS) (1). Subjects born SGA have an increased risk of developing permanent metabolic changes as a result of intrauterine programming, leading to increased cardiometabolic risk in adulthood, including hypertension, excess abdominal fat deposition and type 2 diabetes (2). An appropriate lifestyle, based on a balanced diet and adequate physical activity, is the primary preventive intervention for reducing long-term cardiometabolic risk. To our knowledge, while physical activity and aerobic capacity have been extensively investigated in adolescents or adults born preterm (3), no data on cardiovascular fitness in children born SGA have so far been reported. The aim of this prospective study was to evaluate cardiovascular fitness capacity in a group of 22 consecutive children born SGA at term, defined as a gestational age of between 37 and 42 weeks, and referred to the Endocrinology and Diabetes Unit of the Bambino Ges u Children’s Hospital between January 2012 and September 2012. The SGA children were compared to 21 healthy children born at an appropriate for gestational age, with a birth weight of > 2 SDS and <+2 SDS at term, matched for age, gender and body mass index. Children with a birth weight of < 2 SDS were diagnosed as SGA (1). All the SGA children showed catch-up growth that was defined as having attained a height centile within the midparental height range (4). Children with intrauterine growth restriction (IUGR) defined as a weight below the 10th percentile for its gestational age by ultrasound measurements were excluded (5). The control group was recruited on a voluntary basis in the outpatient clinic and comprised children referred to our hospital for minor surgery or electrocardiographic screening. None of the children in either of the groups took part in organised physical activities. Subjects with chronic diseases, genetic syndromes or on chronic therapies were excluded from this study. All children underwent assessment of their anthropometric and physical activity parameters. Puberty development was clinically assessed on the basis of secondary sex characteristics (6). Only subjects with stage I or II gonadal or breast development were considered for the analysis. Maximal cardiovascular fitness capacity was assessed using the standard Bruce treadmill test (7) with increasing belt speed and per cent grade (Tecnogym Runrace, Tecnogym Gambettola, Italy). The parameters measured during the cardio pulmonary exercise test were as follows: time of exercise, maximal oxygen uptake (VO2 max) (L/min and mL/kg/min), maximum heart rate and maximum blood pressure. The cardiopulmonary exercise test was considered adequate if one or more of the following conditions were achieved: at least 80% of the maximum predicted heart rate (determined as 220 b/m minus age), a respiratory exchange ratio of 1.0 for a period of at least one minute or exhaustion of the subject (7). Time of exercise, maximal oxygen uptake and maximum heart rate and blood pressure were also calculated as a percentage of predicted values, as previously reported (8,9). The same physician performed all the examinations. Metabolic profile was analysed in the SGA patients by routine laboratory analyses, including the oral glucose tolerance test (10). The homoeostasis model assessments of fasting insulin resistance (HOMA-IR) (11) were calculated as the index of insulin resistance derived from basal values of glucose and insulin. The whole-body insulin