Impact of extreme prematurity or extreme low birth weight on young adult health and well-being: the Victorian Infant Collaborative Study (VICS) 1991-1992 Longitudinal Cohort study protocol

Introduction Infants born extremely preterm (EP, < 28 weeks' gestation) or with extremely low birth weight (ELBW,< 1000 g) in the era when surfactant has been available clinically are at high risk of health and developmental problems in childhood and adolescence. However, how their health and well-being may be affected in adulthood is not well known. This study aims to compare between EP/ELBW and normal birthweight (NBW) controls: (1) physical health, mental health and socioemotional functioning at 25 years of age and (2) trajectories of these outcomes from childhood to adulthood. In addition, this study aims to identify risk factors in pregnancy, infancy, childhood and adolescence for poor physical health and well-being in EP/ELBW young adults. Methods and analysis The Victorian Infant Collaborative Study (VICS) is a prospective geographical cohort of all EP/ELBW survivors to 18 years of age born in the State of Victoria, Australia, from 1 January 1991 to 31 December 1992 (n=297) and contemporaneous term-born/NBW controls (n=262). Participants were recruited at birth and followed up at 2, 5, 8 and 18 years. This 25-year follow-up includes assessments of physical health (cardiovascular, respiratory and musculoskeletal), mental health and socioemotional functioning. Outcomes will be compared between the birth groups using linear and logistic regression, fitted using generalised estimating equations (GEEs). Trajectories of health outcomes from early childhood will be compared between the birth groups using linear mixed-effects models. Risk factors for adult outcomes will be assessed using linear and logistic regression (fitted using GEEs). Ethics and dissemination This study was approved by the Human Research Ethics Committees of the Royal Women's Hospital, Mercy Hospital for Women, Monash Medical Centre and the Royal Children's Hospital, Melbourne. Study outcomes will be disseminated through conference presentations, peer-reviewed publications, the internet and social media.