How baby’s genes influence birth weight and later life disease

Genetic differences could help to explain why some babies are born bigger or smaller than others, according to new research from the Early Growth Genetics (EGG) Consortium. An international collaboration of researchers including experts from the University of Bristol's School for Social and Community Medicine and the Avon Longitudinal Study of Parents and Children have found that genetic differences provide an important link between the biology contributing to an individual's early growth and their chances of developing conditions such as type 2 diabetes or heart disease in later life. The large-scale study could help to target new ways of preventing and treating these diseases. It concluded that a substantial proportion (at least one-sixth) of the variation in birth weight is down to genetic differences between babies. This is seven to eight times more variation than can be explained by environmental factors already known to influence birth weight, such as the mother smoking during pregnancy or her body mass index (a measure of obesity) before pregnancy starts. It has been known for some time that babies whose birth weight is well below, or well above, average have a markedly increased risk of diabetes many decades later. Until now, many researchers have assumed that this link reflects the long-term impact of the nutritional environment in which the foetus develops: in other words, that events in early life can "set up" an individual's body in ways that make them more prone to disease in later life.