 The Southampton Womens Survey SWS is a prospective study of mothers and children, established in 1998. A general population sample of 12,583 non-pregnant women, aged 20-34 years resident in Southampton was recruited 1998-2002. All women were visited at home by a research nurse and characterised in detail, including assessments of diet, lifestyle and body composition. Between 1998 and 2007, 3158 of the SWS women became pregnant, and went on to deliver a live singleton infant. These women were followed up in through pregnancy and their children have been assessed in a number of follow-up studies in infancy and childhood. These have included repeated assessments of diet, anthropometry and body composition, as well as detailed functional measurements at specific ages, and are ongoing. 