Women who consume a high amount of sugar while pregnant may increase the risk of their child having allergies and allergic asthma, a new study has found.

Until now, there has been very little research carried out on this topic, so UK researchers decided to investigate further.

They looked at almost 9,000 mother-child pairs, assessing the mothers' intake of free sugars during pregnancy, and allergies and asthma in the women's children at the age of seven.

Free sugars are simple sugars added to foods by the manufacturer or consumer. They are also sugars that are naturally present in honey, syrups and fruit juices. These are different to those found naturally in foods such as the milk sugar, lactose, found naturally in milk/milk products and the fruit sugar, fructose, which is naturally present in whole fruits.

While the study found only a weak link between free sugar intake during pregnancy and asthma overall, there was a strong link found with allergy and allergic asthma, which is when a child is diagnosed with asthma and has positive skin tests to allergens.

In fact, the children of the 20% of mothers with the highest maternal sugar intake had a 38% increased risk of having allergies and a 101% increased risk of having allergic asthma, compared to the children of the 20% of mothers with the lowest maternal sugar intake.

No link between sugar intake and eczema or hay fever was found. The children's intake of free sugars in early childhood was also found to have no link with the risk of allergies.

"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. However, given the extremely high consumption of sugar in the West, we will certainly be investigating this hypothesis further with some urgency.

"The first step is to see whether we can replicate these findings in a different cohort of mothers and children. If we can, then we will design a trial to test whether we can prevent childhood allergy and allergic asthma by reducing the consumption of sugar by mothers during pregnancy," commented the study's lead researcher, Prof Seif Shaheen, of Queen Mary University of London.

Pending further studies in this area, the researchers recommend that pregnant women ‘follow current guidelines and avoid excessive sugar consumption'.

Details of these findings are published in the European Respiratory Journal.