Stress during pregnancy may affect an unborn baby's development in the womb, research suggests.

Scientists who boosted levels of a natural stress hormone in pregnant mice found that while it caused mothers to eat more, the transport of energy-giving glucose to the foetus was impaired.

Lead researcher Dr Owen Vaughan, from Cambridge University, said: "Together with previous work, the findings show that maternal glucocorticoids regulate foetal nutrition.

"Higher glucocorticoid hormone levels in the mother, as seen in stressful conditions, can reduce glucose transport across the placenta and lead to a decrease in foetal weight."

In the mouse study, the scientists raised levels of the glucocorticoid hormone corticosterone at three different times during pregnancy.

The results, published in The Journal of Physiology, showed that under stress certain genes in the placenta were modified.

One of the altered genes, Redd1, is believed to interact with pathways within cells that regulate growth and nutrient uptake.

Dr Vaughan added: "Glucocorticoid levels in pregnant women may determine the specific combination of nutrients received by the foetus and influence the long-term metabolic health of their children as a result.

"This could have implications for women stressed during pregnancy or treated clinically with glucocorticoids, if the mechanisms are similar in humans."

Further research may uncover drug targets that could "rescue" foetal growth when stress hormones are raised during pregnancy, said the scientists.