A hundred years ago, when tuberculosis and rheumatic heart disease were common, the proposition that the childhood environment affects adult health would have been selfevident. This proposition may still hold, even though infective disease has given place to degenerative disease. Studies in Norway, Finland, Britain, and the United States have shown that death rates from cardiovascular disease are inversely related to adult height, and geographical differences in cardiovascular mortality are related to past differences in infant mortality.'7 These findings have been interpreted as evidence that adverse living conditions during childhood, such as poor housing and diet, increase the risk of ischaemic heart disease. 4 Case-control studies have generally supported this8-'2: patients with myocardial infarction have higher infant death rates among their siblings, 89 are more likely to come from larger families, and are more likely to have fathers who were unemployed.'0 Now studies in Finland show that men with ischaemic heart disease had worse socioeconomic con-ditions in childhood (p 112 1)'2-an observation also made in Britain. 9

The completeness of infant mortality records in England and Wales from 1911 onwards has allowed detailed geographical comparisons of the relation between infant mortality 70 years ago and mortality from cardiovascular disease today. Differences in the death rates from cardiovascular disease among the 212 local authority areas of England and Wales are closely related to past differences in neonatal mortality. 6"'Most neonatal deaths were associated with low birth weight, and rates were high in areas where mothers had poor health and high death rates during childbirth.'4 1'These findings suggested that research should be redirected towards the intrauterine environment rather than the environment in later childhood-housing, family income, diet, and other influences. The Medical Research Council employed a historian to search for old records of birth