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Stress in pregnancy could produce bigger babies

Common life stresses such as work problems were found to have an effect Keystone

Everyday stress in pregnant women may lead to bigger newborns and earlier births, a Basel University study has found.

The results, published in the American Psychosomatic Society journal, are the first to tie common stress factors experienced by pregnant women, such as money worries or relationship problems, to greater growth in babies.

Similar studies in the past have looked at the impact of severe stress, such as natural disasters or the death of a partner, and in contrast have showed such factors leading to smaller newborns.

The Basel researchers discovered that common stress can increase babies’ body weight and length, as well as their abdominal and head circumferences.

Among the 78,017 women studied, common stress also led to earlier births, three hours to two days ahead of due dates.

The issues of premature births and growth restrictions in the uterus have become a major public health concern, the study authors say.

Both issues have been linked to a higher risk of medical problems and death during infancy. Adults who were preterm or had restricted growth in the womb also have an increased risk of dying of cardiovascular and metabolic disease.

First author Marion Tegethoff told more and more research was been done into the prenatal origin of diseases in foetuses. With some studies already carried out on the impact of severe stress, the Basel team decided to focus on minor forms of stress that tend to affect the wider population.

“Stress in a job, stress with friends, or lighter emotional problems like anxiety or depression affect many pregnant women. We wondered if this already has an effect on the foetus,” she said.

Different stress

For the study, Basel University’s Department of Psychology used data from the Danish National Birth Cohort study of women giving birth between 1996 and 2002.

The team also looked at emotional symptoms such as anxiety and mild depression, and found they too led to earlier births. But unlike common life stress, these symptoms resulted in smaller sized newborns.

“The new thing about our study is that we used different kinds of stress. The association with foetal growth really seems to depend on the type of stress,” said Tegethoff.

“On the one hand this is basic research into how stress can really affect the foetus. It would be interesting to follow up the children and see if there is a link to the child’s health later on.

“Is there a relation between this growth that we have observed and a later risk of disease, for example.”


Liliane Maury Pasquier, president of the Swiss Midwives Association, welcomed the addition of more research into the field.

“There is a lot to be done on the question of stress. Not much actual research has been carried out, although there is a lot that we believe to know according to popular wisdom,” she told

“There are a lot of pressures on women today and on pregnant women in particular and it is true that these pressures can be conflicting – between work, worrying about one’s physique, and so on – and can become a stress.”

“Stress can play a role during pregnancy but we do not know much about it.”

Jessica Dacey,

The number of births in Switzerland is on the rise, according to the latest figures from the Federal Statistics Office.

There were 76,700 babies born in 2008: 39,600 boys and 37,100 girls. That’s a rise of 2.9% compared with the previous year. A quarter were of foreign nationality and their number rose by 5% compared with 2007.

Women on average had 1.48 children in 2008.

Mothers are becoming older. In 1970 68.9% of mothers were aged under 30, while in 2008 almost the same proportion (64.7%) were aged 30 and above. The average age of a woman giving birth is 31.

Most babies are born into married couples, and births by single, divorced or widowed women are less common although their number is growing. A total of 17% of babies were born to unmarried women in 2008, an 8.8% rise on 2007.

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SWI - a branch of Swiss Broadcasting Corporation SRG SSR