The 1970 British Cohort Study began life as the British Births Survey and aimed to collect information about all babies born in England, Scotland, Wales and Northern Ireland during a single week in April 1970. More than 17,000 babies were included in the survey.

During the week of the births, the questionnaires were completed by the midwife who had undertaken the delivery, or by a senior midwife. The senior midwives in the hospital and domiciliary services then checked that all questions had been answered before the questionnaire forms were sent to the departments of the Medical Officers of Health to be matched against the notifications of births in each region. Ninety percent of the questionnaires were returned within the first four months, with the last one arriving on 21 December 1970.