Stress increases risk of ‘low birth-weight babies’

Stress levels in pregnant women could adversely affect the foetus. Picture: SWNS
Stress levels in pregnant women could adversely affect the foetus. Picture: SWNS
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ANXIOUS mothers may be at increased risk of low birth-weight babies, say researchers.

Scientists believe that stress during pregnancy could have a negative affect on an unborn baby’s development in the womb.

Researchers 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.

“Together with previous work, the findings show that maternal glucocorticoids [hormones that create a response to stress] regulate foetal nutrition,” lead researcher Dr Owen Vaughan, from Cambridge University, said.

“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.”


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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.

“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.

Lindsay Pattinson, a trained midwife and owner of Edinburgh Hypnobirth, a relaxation technique that helps women to keep calm during pregnancy and childbirth, warned that the new research could stress pregnant women out further.

“I am aware of links between stress and foetal development and there is ongoing research into this area in Edinburgh at the moment, but you have to be careful not to stress people out further,” she said.

“Women may have had something traumatic happen to them during their pregnancy, or may have a fear of giving birth, and we don’t want to them to develop further anxiety.”

This is the latest in a long line of work linking stress in pregnancy to foetal health.

A recent study, published in the journal Archives of Disease In Childhood, found that anxious mothers are more likely to have babies who cry for longer.

University of Edinburgh researchers also recently linked stress in pregnancy to long-term anxiety for babies throughout their lifetime. They said mothers’ wombs and babies’ brains contain a chemical protecting them from stress but some women lack this chemical.