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Artificial sweeteners in pregnancy linked to fatter babies

One year olds’ BMI higher if mums drank artificially sweetened drinks daily in pregnancy

Louise Prime

Tuesday, 10 May 2016

Babies of women who drank artificially sweetened drinks daily during pregnancy were twice as likely to be overweight by the time they reached one year old as babies whose mums drank no such beverages while pregnant, research* has shown. Commentators on the study, published in JAMA Pediatrics, have called** for full clinical trials comparing the effects of maternal consumption of artificially sweetened drinks, sugar-sweetened drinks and water on infant body mass index (BMI).

Because of concerns about the effect on the foetus of excess sugar consumption during pregnancy, expectant women might be tempted to switch to drinks sweetened instead with non-nutritive sweeteners (NNSs). Earlier research has shown that these can, paradoxically, increase the risk of obesity and metabolic disease – but the effect of exposure during pregnancy is little understood.

Researchers in Canada wanted to find out more, so they designed a study to investigate the association of NNS consumption during pregnancy and babies’ BMI. They studied 3,033 pairs of mums (average age 32 years) and babies, comparing data from the mothers’ food diaries kept during pregnancy, and their babies’ BMI at one year old.

During pregnancy, more than a quarter (29.5%) of the women said they drank artificially sweetened drinks; and 5.1% of all the women drank such drinks at least daily. At one year old, the average BMI z score (a measure of deviations in BMI) was 0.19, and 5.1% of all babies were overweight. Compared with babies whose mothers had never drunk artificially sweetened drinks during pregnancy, those whose mothers had drunk them daily were twice as likely to be overweight by one year old. Maternal consumption of drinks containing NNS – but not of sugar-sweetened drinks – was also associated with an increase in babies’ BMI z score.

The study authors pointed out that their results do not prove causation, because of the potential for error in information taken from self-reported diaries. But they said their study does “provide the first human evidence that artificial sweetener consumption during pregnancy may increase the risk of early childhood overweight”. They added: “Given the current epidemic of childhood obesity and the widespread consumption of artificial sweeteners, further research is warranted to replicate our findings in other cohorts, evaluate specific NNS and longer-term outcomes, and study the underlying biological mechanisms.”

Authors of a linked editorial agreed that despite its limitations, the study’s results warrant attention and further research. They suggested: “Experimental studies in animals and small intervention trials among pregnant women can explore mechanisms. Observational cohort studies should incorporate substitution as well as addition models and pay close attention to confounding. Randomised clinical trials substituting ASBs for SSBs [sugar-sweetened beverages] or, equally valuable, water for ASBs would be particularly helpful.”

* Azad MB, Sharma AK, de Souza RJ et al. Association between artificially sweetened beverage consumption during pregnancy and infant body mass index. JAMA Pediatr. Published online May 9, 2016. doi:10.1001/jamapediatrics.2016.0301.

** Pereira MA, Gillman MW. Maternal consumption of artificially sweetened beverages and infant weight gain: causal or casual? JAMA Pediatr. Published online May 9, 2016. doi:10.1001/jamapediatrics.2016.0555.

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