Experts believe stress can affect a mother's unborn child as early as 17 weeks
Unborn children may be affected by their mother's stress as early as 17 weeks into pregnancy, experts claim.
A study found that fetuses are exposed to stress hormones from a young gestational age.
While it is already known that stress experienced by pregnant woman can potentially affect their child, little is known about why or how it happens.
Research published in the journal Clinical Endocrinology found that stress hormones are most likely transferred across the placenta.
A team led by Professor Vivette Glover at Imperial College London, and consultant obstetrician Pampa Sarkar, from Wexham Park Hospital in Berkshire, measured levels of the stress hormone, cortisol, in 267 pregnant women.
They took blood samples from the mother and samples of amniotic fluid from around the baby, which is regarded as a good indicator of the kinds of hormones and substances a fetus has been exposed to.
The experts found that, at 17 weeks or greater, the higher the cortisol levels in the mother's blood, the higher the level of cortisol in the amniotic fluid. The link between the two also gets stronger as the pregnancy advances.
Miss Sarkar said: "We now need to carry out further work to unravel the mechanisms by which maternal stress affects the fetus, both during fetal life and through into childhood.
"We do not wish to unduly worry pregnant women. It should be remembered that one of the best ways for people to avoid general stress is to lead a healthy, balanced lifestyle."