The EFSOCH was a United Kingdom-based prospective birth cohort comprising 986 mother–father–baby triads from central Exeter, designed to investigate genetic and environmental influences on fetal growth and early development. Families were recruited between 2000 and 2004 via the Exeter Maternity Unit database, with eligible families contacted by mail and phone. The cohort included only Caucasian parents with singleton, non-diabetic pregnancies. Over 1,000 parents took part in the initial data collection at 28 weeks’ gestation, and 986 families were followed up. Follow-up assessments were conducted at birth, 12 weeks, 1 year, and 2 years of age.