The possible relation between low-calorie sweeteners and unfavourable pregnancy outcomes, in particular preterm delivery and low birth weight, was originally raised in 2010 by Halldorsson et al. from a study based on the Danish National Birth Cohort (1996– 2002). Another study published in 2012 by Englund-Ogge et al. also examined the possible relation between low-calorie-sweetened and sugar-sweetened beverages and preterm delivery using data from 60.761 women in the Norwegian Mother and Child Study cohort.
In this commentary Carlo La Vecchia presents the limitations of both studies. Specifically, in the Danish study by Halldorsson et al. (2010) the original report presented the results stratified by carbonated and non-carbonated drinks only, and gave a relative risk (RR) of 1.78 for drinkers of ? 4 servings/ day of “artificially sweetened carbonated soft drinks”. This RR estimate was, however, based on 27 cases only (i.e. less than 1% of the cases), a likely selected sub-population. This subgroup may well have other baseline characteristics that influence its risk of preterm birth, and some residual confounding is likely to be present also after multivariate analysis.
Regarding the Norwegian study by Englund-Ogge et al. (2012), the commentary notes that compared to non-users of artificially sweetened beverages, the relative risk (RR) was 1.01 for <1 serving/week, 1.09 for 1– 6 servings/week, 1.20 for 1 serving/day, 1.01 for 2– 3 servings/day and 1.12 for ? 4 servings/day. The test for trend was formally non-significant (p =0.053), and there was no linear dose– risk relation; that is, the RR was 1.01 for both women reporting sporadic use (<1 serving/week) and for those who exhibited regular use of 2– 3 drinks/day.
Furthermore, in this study, La Vecchia and his team pooled the main findings of the Danish and Norwegian studies using standard meta-analytic techniques. Based on the findings of the meta-analysis, there is no evidence that low-calorie beverages have an impact on preterm delivery at any variance from that of sugar-sweetened beverages.