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 Pregnant women who eat large amounts of sugar may be more likely to have children with allergies. 
 
 A study of 9,000 women found that those who ate high levels of sugar during pregnancy were around twice as likely to have a child that went on to develop allergic asthma than woman who ate relatively little sugar. Allergic asthma is the most common form of asthma, and involves allergens provoking the immune system into causing breathing problems. 
 
 “We cannot say on the basis of these observations that high intake of sugar by mothers in pregnancy is definitely causing allergy and allergic asthma in their offspring,” says Seif Shaheen, at Queen Mary, University of London, who led the study. “However, given the extremely high consumption of sugar in the West, we will certainly be investigating this hypothesis further with some urgency.” 
 
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 One theory for how sugar could cause asthma is that large amounts of fructose might trigger an immune response in the body, leading to inflammation in the lungs. Fructose is a sugar found in fruit and corn syrup, and is used widely in processed food. 
 
 Many factors influence a baby’s allergy risk, including exposure to microbes and pollutants, and the type of milk they are fed, says Sheena Cruickshank, at the University of Manchester, UK. “Future studies should take these variables into account so we can understand the full relationship between maternal diet during pregnancy and allergic disease in offspring.” 
 
 Journal reference: European Respiratory Journal 
 
 Read more: Fat vs carbs: What’s really worse for your health? 

 How much sugar a woman eats while she’s pregnant may affect her future children’s risk of developing allergies and allergic asthma, according to a study in the European Respiratory Journal. Although previous research has linked asthma and high-sugar intake in kids themselves, this is the first study to show that mothers’ diets may also play a role. 
 
 The new study analyzed data from nearly 9,000 women who were pregnant in the early 1990s, and from their children, who were tested for asthma and common allergies (like dust mites, cats and grass) at age 7. While pregnant, the women were asked about their weekly consumption of certain food groups and specific food items, including sugar, coffee and tea; their responses were used to calculate their intake of added sugar, not including natural sugars in fruits, vegetables or dairy products. 
 
 The researchers only saw weak evidence to suggest a link between women’s added sugar intake and their children’s chances of developing asthma overall. But when they looked specifically at allergic asthma—in which an asthma diagnosis is accompanied by a positive skin test for allergens—the link was much stronger. Children whose moms were in the top fifth for added sugar during pregnancy were twice as likely to have allergic asthma when compared to children whose moms were in the bottom fifth. 
 
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 Kids of moms with high-sugar diets were also 38% more likely to test positive for an allergen—and 73% more likely to test positive for two or more—than those whose moms stayed away from added sugar. The researchers controlled for several factors that could have also influenced the findings, including social factors and other aspects of the mothers’ diets. 
 
 Not all allergic conditions were linked to maternal sugar consumption, however. No association was found for eczema or hay fever. And contrary to previous studies, no association was found between the children’s own sugar intake (at age 4) and any of their health outcomes at age 7. 
 
 MORE: How To Prevent Peanut Allergies 
 
 The study was not able to show a cause-and-effect relationship. But the authors speculate that high-sugar intake during pregnancy may increase inflammation in developing lung tissue, leaving children predisposed to allergies. “We know that the prenatal period may be crucial for determining risk of asthma and allergies in childhood, and recent trials have confirmed that maternal diet in pregnancy is important,” says first author Annabelle Bedard, a postdoctoral fellow in the Center for Primary Care and Public Health at Queen Mary University of London, via email. 
 
 Bedard believes that consumption of high-fructose corn syrup may be largely responsible. It increased from about 0% to nearly 30% of per capita consumption of refined sugars in the United States between 1970 and 2000. “The dramatic ‘epidemic’ of asthma and allergies in the West in the last 50 years is still largely unexplained,” she says. “One potential culprit is a change in diet.” 
 
 Given the extreme amounts of sugar consumed regularly in Western countries, the study authors say the need for further research is urgent. They hope to conduct clinical trials to see if reducing sugar intake during pregnancy will, in fact, affect children’s health several years later. 
 
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– Pregnant women already have an exhaustive list of foods they’re told to limit or avoid. But a new longitudinal study might make that list longer. Time reports that research published in the European Respiratory Journal found a link between higher added sugar intake during pregnancy and a child's risk of allergies and allergic asthma. In the study, 9,000 pregnant women completed a food questionnaire that asked about 43 food groups and items. When their children turned seven, the kids were tested for common allergies like cats and grass and the mothers were asked about their kids' history with asthma. The researchers found that moms ranked in the highest 20% of added sugar intake had children twice as likely to have allergic asthma than moms in the bottom 20%. According to New Scientist, allergic asthma is the most common form of the respiratory condition and is caused by allergens that bring on breathing problems. The moms eating the most sugar also had kids 38% more likely to test positive for one allergen and 73% more likely for two or more. While the study didn't prove causation, one theory on how added sugar could up the risk of allergies and asthma is that immune reactions to fructose may bring on inflammation in a developing fetus' lungs. “Given the extremely high consumption of sugar in the West, we will certainly be investigating this hypothesis further with some urgency,” the lead researcher says. (Good news for those with peanut allergies: a skin patch may be on the way).