Victorian Infant Collaborative Study

DNA samples were derived from dried blood spots taken for newborn screening when infants were several days of age, after obtaining permission from the participants when they were aged 18 years, or from their parents if they were younger than 18 years. 298 survivors born either <1000 g or <28 weeks’ gestation in the state of Victoria were enrolled in a longitudinal follow-up study, which was approved by the Human Research Ethics Committees at the Royal Women’s Hospital, the Mercy Hospital for Women, Monash Medical Centre, and the Royal Children’s Hospital, Melbourne, Australia. Gestational age was determined by ultrasound estimation before 20 weeks of gestation, or by menstrual history in the minority if no ultrasound dating was available.