Breaking down the microbiology world one bite at a time
Looking at microbes to explain different baby head sizes
Gestational diabetes mellitus (GDM) is hyperglycemia (excess sugar) during pregnancy that can lead to complications like pre-term labor and breathing difficulties. Studies in the past have shown that transferring microbiota from humans suffering from GDM into healthy pregnant mice causes the mice to develop GDM, implying that the gut microbiome plays a crucial role in GDM. It is not understood entirely whether microbiome changes in GDM results in altered development of the infant. So a research group followed pregnant mothers with GDM in Hong Kong through their pregnancy and their infants during the first year monitoring the microbiome and other clinic parameters of health. They had some interesting findings.
While women with GDM had fewer different types of microbes in their gut, their infants had more varied microbes than healthy controls. The reduced diversity of microbes in the women with GBM is linked to glucose intolerance and affects metabolic health. Both our cells and microbes help in digestion. So when the microbiome is altered, our metabolite levels could also be affected. Hence GDM alters microbial diversity both in women and their infants.
Of course pregnancy itself changes the microbiome. Wondering why? In order to accommodate the growing fetus, pregnant women’s bodies need to undergo some changes and these changes are communicated by chemical messengers called hormones. Hormones like estrogen and progesterone increase radically during pregnancy. Increasing hormone production is not a standalone change that can be made, the metabolic pathway needs to be altered to allow for increased hormone production, thus resulting in changing the food sources available for the gut microbes and therefore shifting their composition just like how the birds and insects visiting your garden change when you change the plants in your garden.
Moving to the infants, the GDM leaves its impact on one year olds where GDM infants have higher presence of potentially pathogenic bacteria. This can be linked to a couple of different things. One of the biggest sources of microbiome in infants is from the mother. The infant is exposed to maternal microbiomes and that acts as a starting pool which over time can also be exposed to newer microbes from the environment. So if GDM mothers have altered microbiomes, one would expect similar changes in the infants. Another factor can be differentially utilization of metabolites given the hyperglycemic background during the development of the fetus.
Now the different microbiome in the infant can affect the child’s development. Interestingly, it was seen that male GDM infants had larger head circumference growth rate. This sex-based difference could also be explained by looking at the gut microbiota. The males had increased presence of Clostridium paraputrificum whereas the females had increased presence of Actinomyces. The gut microbiota makes a lot of products that are utilised by the body. One such example would be using microbial products for the synthesis or degradation of neurochemicals. To illustrate the point being discussed here, the authors found that acetate (a two carbon group) degradation which is important for GABA synthesis (a neurochemical messenger) is depleted in GDM mothers with male infants because of the alterations to the microbiota resulting in the male foetuses of GDM mothers going through a different gut-brain axis and growth trajectory.
Microbiome is complicated and linked to us in so many different ways. Explored here was pregnancy and GDM pregnancy effects on microbiome and how that in turns affects the pregnancy and the infant. There is a lot left to be understood but working on this will allow us to one-day correct any dysfunctional metabolic pathways with GDM so that infants have better health and survival outcomes.
Featured image: Generated with Meta AI
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