Fetal programming

From a pathophysiological perspective, 'fetal programming' refers to adaptations made by a fetus in response to adverse intrauterine environments, adaptations targeting the fetus’s survival, adaptations that alter fetal structure and function during the highly plastic period of embryonic/fetal development, lasting adaptations that determine the structural, metabolic and physiological characteristics of the individual throughout the developmental stages of postnatal life, characteristics that can predispose the individual in later life to maladaptations in response to environmental conditions differing from those that the individual adapted to during fetal development. The adaptations 'program' the newborn infant for the the responses it makes to its environment throughout its lifetime.

In a 2004 review, pioneer of fetal programming phenomena, David Barker summarized the following as 'key teaching points':

Studies have shown an association between low birthweight and risk for cardiovascular diseases and other chronic conditions [e.g., hypertension, stroke, metabolic syndrome, type 2 diabetes] later in life. Developmental plasticity describes the fetuses ability to respond to their mother’s diet in utero. Low birthweight and inadequate nutrition early in life may lead to lifelong alterations in the body’s setting of metabolism and hormones as well as the number of cells in key organs. Low birthweight followed by rapid weight gain during infancy has been shown to further increase risk for disease.

Examples of fetal programming in humans

In 1986, David Barker and C Osmond reported on their studies of the relationships among infant mortality, childhood nutrition, and adult ischemic heart disease in England and Wales. By geographical regions, past infant mortality rates, highest where poverty was greatest, associated positively with present occurrences of ischemic heart disease, whereas increasing heart disease presently associated with increasing prosperity. From their analysis the investigators suggested that “poor nutrition in early life increases susceptibility to the effects of an affluent diet”.

Fetal programming applies also to age-related cognitive decline. A long term follow-up study in men by Katri Raikkonen and colleagues showed that lower cognitive ability at mean age 67.9 years associated with lower birth-weight, birth-length, and birth-head-circumference. Similarly, cognitive decline after age 20 years associated with those lower measures of intrauterine physical growth. The investigator found that in "predicting resilience to age related cognitive decline, the period before birth seems to be more critical" compared to the period of infancy.

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