Sweetened soft drinks linked to preterm birth

Sweetened (sugar-sweetened and artificially-sweetened) drinks may be linked to preterm birth, according to a recent joint study between Norwegian and Swedish researchers. It is important to prevent preterm birth since it may lead to early death, diseases in infancy and childhood as well as long-term disability.

At the Norwegian Institute of Public Health, data from the Norwegian Mother and Child Cohort Study (MoBa) are analyzed to find the causes of preterm birth. Links to life style habits, diet, infections and genetic factors are investigated. As yet, no strong factors that can explain why preterm birth occurs have been identified, but an association with body mass index and diet have been found.

In a similar Danish cohort, it was reported that artificially-sweetened, but not sugar-sweetened soft drinks were associated with a small increase in the risk of preterm birth. We have studied the same data in MoBa, and find that for those women drinking more than one daily serving of sugar- or artificially-sweetened drinks, there was a small increased risk of preterm delivery (before week 37 in pregnancy).

The women who consumed a higher amount of sugar and artificially-sweetened drinks were more likely to have a higher body mass index, a lower education, to be daily smokers or to be single women. The statistical analyses adjusted for the possibility that factors more common among those consuming soft drinks, such as smoking, young age and high body mass index could explain preterm birth, but other similar factors could still be involved.

Although the Norwegian data confirmed the Danish findings regarding an association between artificially-sweetened drinks and preterm delivery, we cannot at the present stage claim that artificial sweeteners have a causal relationship to preterm birth. While the Danish study only found an increased risk for artificially-sweetened beverages, we also found an increased risk for preterm birth for sugar-sweetened beverages. This difference gives reason for caution. More studies are needed, ideally as controlled trials, but in general, daily intake of sweetened drinks should be avoided.

The prospective study was a collaboration between researchers at the Norwegian Institute of Public Health, Sahlgrenska University Hospital and Sahlgrenska Academy in Gothenburg, Sweden. 60,761 pregnant women were included in this study. They completed three questionnaires during pregnancy about their lifestyle and diet. Data from their birth records in the Medical Birth Registry were linked to the MoBa database.

The Norwegian Mother and Child Cohort Study is a unique longitudinal study that recruited more than 100,000 pregnant women in the years 1999-2008, collecting detailed questionnaire data and biological samples from the participants.