Exposure to excess hormones in the womb increases risk of heart disease and diabetes

Babies exposed to excess hormones in the womb are not only at increased risk of developing heart disease and diabetes in later life but can pass these risks to their children.

A University of Edinburgh team, reporting their findings in the American Journal of Physiology, has discovered that the genetic risks to the health of future generations can come from either parent.

Scientists believe that exposure of a baby to adverse conditions before birth can ‘programme’ altered growth and development, resulting in reduced birth weight and a tendency to develop disease in later life. One factor influencing this might include exposure of the baby to excess stress hormones (glucocorticoids) before birth. Glucocorticoids are present in both mother and baby, and are also widely used as a treatment in pregnancy in threatened or actual premature delivery, to improve the baby’s development and chances of survival.

Now, the medical scientists from the University have shown in laboratory tests that low birth weight and the increased risk of diabetes can be passed by a mother or father to their own children affected by ‘programming’.

Researcher Dr Mandy Drake explained:“ The baby is normally protected from the high levels of steroid hormones in the mother by the placenta. However, studies have shown that low birth weight babies have been exposed to higher levels of the mother’s own steroid hormones crossing the placenta during pregnancy. We have discovered that both male and female rats exposed to steroids during development in the womb can pass on these risks to their offspring and this ‘intergenerational’ effect is not entirely explained by problems in the mother such as reduced body size or diabetes risk.

“We believe that exposing the developing baby to excess steroid hormones can alter the expression of key genes which affect foetal growth and later risk of disease which can be passed on to the next generation. We are now investigating the mechanisms behind this to try and explain the short and long-term complications associated with low birth weight in humans, which may also have a significant impact upon the health of subsequent generations. The better news is that the effect appears to be lost in the third generation. This may explain why some diseases appear to run in families for a couple of generations, then peter out.”