Breast milk has been reported as a multifunctional fluid, which includes human milk oligosaccharides (HMOs) that may influence the development of the gut microbiota and the training of a newborn baby’s immune system.

A recent pilot study led by Dr. Mireille van Poppel and colleagues from the University of Graz and BioTechMed-Graz in Austria has revealed that during pregnancy, HMOs are present in maternal serum and show associations with maternal body composition in normal-weight women. These findings suggest these molecules might have systemic implications for both maternal and fetal health during pregnancy.

In an attempt to explore the effects of HMOs on maternal metabolism, Jantscher-Krenn and colleagues from the University of Graz in Austria followed a sample of 87 overweight or obese pregnant women at increased risk of gestational diabetes mellitus (GDM).

All HMOs measured in serum (2’-fucosyllactose, lactodifucotetraose, 3’-sialyllactose, and 3’-sialyllactosamine) increased from early to mid- and late pregnancy.

Furthermore, researchers found different associations between HMOs in early pregnancy and maternal metabolic outcomes in late pregnancy, with 3’-sialyllactose and 3’-sialyllactosamine in serum positively associated with changes in fasting glucose at 24 and 32 weeks. In addition, lactodifucotetraose was positively associated with changes in insulin and insulin resistance (HOMA-index) at 24 weeks.

The secretor status of pregnant women (secretor positive vs. secretor negative) did not have an influence on the serum levels of all studied HMOs.

Although a previous study has shown that a certain type of HMO improves glucose tolerance and insulin sensitivity in diet-induced obese mice, this is the first time HMOs have been linked to glucose homeostasis in humans.

The authors also developed a statistical model that featured several parameters—fasting glucose, pre-pregnancy body mass index, gestational weight gain, age, parity, smoking, history of macrosomia and 3’-sialyllactose in early pregnancy—to predict the development of GDM. When compared with fasting glucose, the serum levels of 3’-sialyllactose in early pregnancy were better predictors of GDM development in pregnancy.

These results suggest that HMOs may contribute to explaining how pregnancy-induced metabolic changes can drive an increased risk of GDM in overweight and obese pregnant women.

On the whole, this new research highlights a novel role for HMOs in regulating maternal glucose metabolism beyond their known biological functions. Although the causal contribution of HMOs to GDM in overweight and obese pregnant women deserves further research, these findings highlight the relevance of HMOs for maternal metabolism and as a predictive biomarker for predicting GDM.


 Jantscher-Krenn E, Treichler C, Brandl W, et al. The association of human milk oligosaccharides with glucose metabolism in overweight and obese pregnant women. Am J Clin Nutr. 2019. doi: 10.1093/ajcn/nqz202.