Expectant mothers advised to avoid excess consumption of fructose

Eating too much sugar in pregnancy doubles child’s asthma risk, study finds

High levels of sugar consumption during pregnancy doubled the chances of a child developing allergic asthma, according to a UK study of almost 9,000 mothers and their children.

Allergy risk was increased by up to 73 per cent, but no link was found between sugar exposure in the womb and rates of eczema or hay fever.

The team from Queen Mary University of London compared the 20 per cent of mothers who consumed the most sugar when pregnant with the same proportion who consumed the least. The research focused on fructose, a type of sugar found in fruit, fruit juice, sugary drinks and corn syrup. It is widely used in processed foods.

Lead researcher Prof Seif Shaheen said: “We cannot say on the basis of these observations that a high intake of sugar by mothers in pregnancy is definitely causing allergy and allergic asthma in their offspring.


Given the extremely high consumption of sugar in the West, they would certainly be investigating this hypothesis further “with some urgency”, he added. The first step was to see whether they could replicate these findings in a different cohort of mothers and children.

If that was successful, he said, they would design a trial to test whether they could prevent childhood allergy and allergic asthma by reducing the consumption of sugar by mothers during pregnancy.

“In the meantime, we would recommend that pregnant women follow current guidelines and avoid excessive sugar consumption,” he advised.

The study, published in the European Respiratory Journal, drew on data from the Avon Longitudinal Study of Parents and Children (ALSPAC) – also known as the "Children of the 90s" study, the investigation has followed the progress of children whose mothers were pregnant in the early 1990s.

Foetal consumption

The sugar link with asthma may be explained by high intakes of fructose triggering an immune response leading to inflammation in developing lungs, the scientists said. Freely-consumed sugar in early childhood had no effect on the results, researchers said. It was foetal sugar exposure that was important, they underlined.

The research indicated an association between consuming fructose during pregnancy and asthma up to the age of seven, said Dr Des Cox, consultant respiratory paediatrician at Our Lady's Children's Hospital in Crumlin, Dublin. While it demonstrated an "association", further research was needed to prove consumption in this way causes asthma, he told The Irish Times. The ALSPAC study was "a trustworthy source" and produced important findings over many years, he said.

There was no indication if the asthma persisted throughout childhood, but it was interesting that the link was found independent of a child’s intake of sugar, he added.

‘Western diet’

Further research was also needed, he added, to understand the biological mechanism associated with fructose consumption. “With the ‘western diet’, intake has increased dramatically over the past 30 years.”

Other studies have suggested increased intake of fructose by children is linked to asthma, but he understood this was the first suggesting foetal exposure may be a cause.

While it was clear that smoking in pregnancy had a detrimental effect on a foetal development, further investigation would be needed to provide definitive advice on fructose consumption.

The Royal College of Physicians of Ireland had a policy group that examined research on childhood obesity, including consumption of sugary drinks, Dr Cox said. When the fructose research was completed, it would update its advice.

Additional reporting: PA

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times