Cohort profile: The Hertfordshire Ageing Study (HAS)

We have previously described the discovery of a unique set of infant records collected in Hertfordshire between 1911 and 1948.1 The historical data for births between 1911 and 1930 were linked to the NHS central register and showed that small size at birth and during infancy was associated with increased risk of cardiovascular mortality in men and women.2,3 These were the first studies based on individual data to suggest that adverse environmental influences acting in utero and during infancy might increase the risk of cardiovascular disease mortality in later life. Detailed physiological investigations of surviving men and women born in Hertfordshire between 1920 and 1930 and still living there in the early 1990s were subsequently conducted and allowed investigation of morbidity. Studies based on men and women resident in East Hertfordshire demonstrated that small size at birth and during infancy was associated with increased risk of developing coronary heart disease