The hypothesis largely survives one ordeal but not another

Papers p 897

That antenatal experience could have dire consequences is ancient folklore. In 1921 Stockard gave scientific form to the idea in the “critical period” hypothesis: failure of a developing organism to progress from one stage of development to the next within preset time limits could lead to a permanent deficit. Since then several studies have addressed related hypotheses, though mostly in animals. From the 1950s human observational studies reported effects in later life of various exposures—for example, to radiation,1^–3 famine,4 and viruses.5 In a large number of more recent publications, Barker has elaborated the idea that fetal experience might “programme” cardiovascular health states in adult life. He has been ingenious in seeking out birth records of cohorts of a half century ago and more. Studies using such sources face some irreparable difficulties—for instance, incomplete samples and attrition on follow up with selective bias, inadequate as well as missing records, and the absence of data crucial for controlled analysis.

Some of these problems are being better resolved in later datasets assembled for long continued longitudinal studies. An analysis from one such birth cohort study in New Zealand appears in this week's issue.6 This analysis also addresses a second—entirely reparable—problem previously discussed by one of us.7 This is the observation that Barker's studies, fertile as they have been in stimulating life course studies, do not …