Severe kidney disease, which may need lifelong treatment with dialysis and transplantation, is more common in people from a South Asian background. One explanation is that South Asian babies have smaller kidneys that are more prone to damage over the child’s life. Using ultrasound of the kidneys in over 1500 mothers at 34 weeks of pregnancy in the Born in Bradford (BiB) study we showed that South Asian babies had smaller kidneys than White British babies even after differences in their birth weight were allowed for. We will now follow-up these children at age 8-11 as part of the larger BiB follow-up and take a small blood and urine sample to see whether kidney function differs between south Asian and White British children and if so whether this is explained by kidney size at birth.