How Is the Child Exposed to Mum’s Microbiome?
This transfer of microbes from mother to child is fundamental for building a healthy infant microbiome, crucial for immune system maturation, infant growth, and brain development. (1) Up until quite recently, the intrauterine environment was thought to be sterile, but this hypothesis has been called into question lately, with emerging evidence that transmission of gut bugs from mum to bub may occur during pregnancy, not just during delivery. (1) It is not understood just yet how much of an impact this transfer of microbes to the foetus during pregnancy will have on the infant’s gut microbiome and overall health throughout the course of their life. (2) Of course, during birth, and immediately after birth, the baby receives a huge and diverse dose of microbes from mum and surroundings, and this significantly influences the make up of baby’s microbiome. (2)

Mother’s Pregnancy Diet Impacts Bub’s Gut Health
Although research into the effect of the maternal diet on offspring gut health is still in its early days, promising findings demonstrate the significance of a mother’s diet during pregnancy, and the impact this has on the infant’s microbiome. (1) The mother’s gut microbiome changes progressively during pregnancy, and plays a significant role in determining the composition of the offspring gut microbiome. (3) Diet is a major influence on maternal gut microbial alterations, and it is therefore no surprise that what a woman eats during pregnancy appears to impact the trajectory of baby’s microbiome development. (3)

Recent studies have highlighted that excess maternal weight gain or inflammation during pregnancy can significantly alter the transfer of microbes from mum to bub, with the knock-on effect of altering the way in which the baby’s gut microbiome develops once born. (1)
Although human studies are limited, certain strains of gut bugs have been associated with the mother’s diet during pregnancy. (3) For example, a high fat maternal diet is associated with a decreased abundance of Bacteroides and Enterococcus in the baby’s gut (3). Also, mothers who consume the recommended amount of fish during pregnancy are more likely to have babies with a Bifidobacterium-dominant gut. (3)

The Influence on Disease Across the Lifespan
The mother’s diet during pregnancy has been associated with the development of a number of different diseases over the lifespan of the offspring. (1, 3). For example, an obesity-associated maternal gut microbiome may lead to a state of imbalance in the gut (known as dysbiosis) for the infant, which can then lead to obesity later in life. (3) Furthermore, an obesity-associated maternal microbiome has been shown to alter the infant’s immune response, increasing the risk of developing asthma and other inflammatory diseases. (3) The mum’s diet during pregnancy may also impact the brain development of the child. It is thought that this occurs via the gut and brain interactions, and that an imbalance in certain strains of bacteria within the gut may affect the ‘early programming’ of the infant brain. (4) On a more positive note, there is also evidence that a good quality diet during pregnancy, characterised by high intakes of vegetables, fruits, nuts, seeds, legumes, and omega 3 fatty acids, may help to reduce the child’s risk of developing a mental illness or hyperactivity-inattention later in life. (5, 6).