Some environmental influences are suspected as having particularly longterm effects on health, in that they may be experienced in the early years of life but their major health effects occur several decades later. Both heart and respiratory disease are among the adult diseases for which potential early life influences have been suggested. Evidence relating to heart disease was provided by a Norwegian study by Forsdahl (1977). He reported that deaths from ischaemic heart disease in the 1970s were correlated with infant mortality around the time of birth of those dying in the 1970s. Taking infant mortality as an index of deprivation in childhood, he hypothesized that nutritional deprivation in childhood followed by relative affluence increased the risk of ischaemic heart disease in adult life. Similarly for adult respiratory disease, evidence for a role of childhood influences became available in the 1970s: in a prospective analysis, a higher rate of symptoms was found in adults who had experienced childhood respiratory illness (Colley et al. 1973).