Exercise Capacity and Heart Function in Post-term born Adolescents

Abstract

Recent research on children born post-term (≥ 42 weeks gestation) suggest they have metabolic abnormalities including reduced insulin sensitivity, dyslipidemia and alterations in blood pressure indicative of a later risk of hypertension. These abnormalities are similar to those previously reported in small for gestational age (SGA) and preterm children who have a higher incidence of adverse health outcomes in adulthood, including diabetes, obesity, reduced exercise capacity and cardiac structural and functional changes. To date there have been no reports investigating exercise capacity and cardiovascular function in post-term children and adults. Aim: To determine whether post-term adolescents have a reduced aerobic capacity and alterations in cardiovascular function compared to term born adolescents. Methods: Gold standard measurement techniques were used in the measurement of body composition (DEXA scan), exercise capacity (VO2max) and cardiac structure and functional changes both at rest and submaximal exercise using a cardiac MRI scan with a supine ergometer. 24-hour ambulatory blood pressure assessments as well as a fasting blood test were also performed. Results: 51 participants were recruited; 25 post-terms and 26 controls aged between 12 and 20 years. All post-terms were ≥ 42 weeks gestation and controls were born at term between 37-41 weeks gestation. VO2max was lower in the post-term vs control group with greater differences seen in the European population. (46.32±1.47 vs 51.40±1.23, p=0.041). There were no differences in cardiac output (CO) and stroke volume (SV) , however ejection fraction (EF) during exercise was higher in the female population born postterm vs those born at term. (67.40±1.00 vs 62.41±1.62, p=0.037). Conclusion: The data show that all the post-terms have reduced VO2max with males being more affected than females. However measurements of central cardiac function showed subtle differences in blood pressure between the two groups. Hence we hypothesize that the reduction in exercise capacity could be contributed by changes in the peripheral vascular system.