High maternal sugar intake during pregnancy may increase the risk of allergy and allergic asthma in children, according to an early study led by Queen Mary University of London (QMUL) involving University of Bristol researchers and almost 9,000 mothers and their children (University of Bristol, 2017).

While some research has reported an association between a high consumption of sugar containing beverages and asthma in children, there has been little study of the relationship between maternal sugar intake during pregnancy and allergy and asthma in children.

The team used data from a world leading birth cohort study, the Avon Longitudinal Study of Parents and Children (ALSPAC), also known as Children of the 90s. The cohort recruited mothers who were pregnant in the early 1990s and has been following up their children ever since.

The current study, which is published in the European Respiratory Journal, analysed associations between maternal intake of free sugars in pregnancy and allergy (defined by positive skin tests to common allergens, namely dust mite, cat and grass) and asthma at the age of seven.

While there was only weak evidence for a link between free sugar intake in pregnancy and asthma overall, there were strong positive associations with allergy and allergic asthma (where the child was diagnosed with asthma and had positive skin tests to allergens).

When comparing the 20% of mothers with the highest sugar intake versus the 20% of mothers with the lowest sugar intake, there was an increased risk of 38% for allergy in children (73% for allergy to two or more allergens) and 101% for allergic asthma. The team found no association with eczema or hay fever.

Lead researcher Professor Seif Shaheen from QMUL 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. 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. In the meantime, we would recommend that pregnant women follow current guidelines and avoid excessive sugar consumption.”

The team speculate that the associations may be explained by a high maternal intake of fructose causing a persistent postnatal allergic immune response leading to allergic inflammation in the developing lung.

The researchers controlled for numerous potential confounders in their analyses, such as background maternal characteristics, social factors and other aspects of maternal diet, including foods and nutrients that have been previously linked to childhood asthma and allergy.

Importantly, free sugar intake in early childhood was found to have no association with the outcomes seen in the analysis.

As the study is observational, it does not prove a causal link between maternal sugar intake and allergies or asthma. A randomised controlled trial would be needed to definitively test causality.

The study was funded by a European Respiratory Society long-term fellowship.