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A revolutionary new concept -- that the bacteria in our bodies is essential to our health -- is only just filtering down into modern day obstetrics. The health of our next generation depends on it.
In the conventional model of pregnancy and birth, a woman continues with life as usual until she gets pregnant, navigates a perilous 9.5 months rife with fear-inducing tests, and hypermedicalization of the process of gestation, and then deposits a baby, no matter what method, into the hands of a pediatrician who sees that baby as a receptacle for pharmaceutical products aimed at correcting physiologic mistakes and deficiencies.
As Maya Angelou says, "We did then, what we knew how to do. Now that we know better, we do better."
An effort to do better must be characterized by an appreciation of the most powerful determinant of not only our health, but our very existence in the fabric of life on this earth – the microbiome. In a powerful essay, A holobiont birth narrative: the epigenetic transmission of the human microbiome, the mother-baby unit is reconceptualized to include the microbial populations in the mother, fetus, and then infant. These microbial communities are reconfigured throughout pregnancy, influenced by birth modality, and by breastfeeding in a way that reflects our co-evolution with the microbial world. In this way,
"Birth is the process of leaving of one symbiotic association system and forming another."
Obstetrics has traditionally regarded the woman and fetus as two largely separate entities coexisting during gestation, a perspective upended by the advent of epigenetic science and our understanding of the relevance of a woman's lifestyle preconception and during pregnancy. From a gene-centric paradigm, pregnancy complications were not preventable, and genes ruled any manifest pathology. Through the lens of the holobiont, however, genetic information passed from mother to baby includes nuclear, mitochondrial, and bacterial genes, and the bacteria themselves carry out many epigenetic processes that influence the expression of genes including detoxification of chemicals, production of nutrients, and foods.
An appreciation for holistic pregnancy care and birthing – the midwifery model – looks at the mother-baby unit and prizes the powerful dialogue between the two. One of the more profound examples of bidirectional influence is that of microchimerism, or the influence of the baby on the mother's physiology, a near sci-fi suggestion of cellular enmeshment between mom and baby.
The Puppet Masters
Passing on the right flora from the mother's gut during a vaginal birth, is acknowledged to be the most important role of the maternal micriobiome. It turns out that there are more tasks on the bacterial to-do list including:
- Colonization of the placenta, primarily by maternal oral bacteria
- Induction of adiposity or weight gain as the flora changes over the course of the pregnancy to reflect a dominance of Proteobacteria and Actinobacteria between weeks 13 and 33 in preparation for breastfeeding.
- Insulin resistance, a natural means to help support glucose availability to the fetus, but also one that can lead to gestational diabetes when coupled with the wrong diet.
- Influence food cravings that suit propagation of dominant flora.
Depending on the setting of colonization, gut microbiota determine what bacteria may stay, and what pathogens should go. Acceptance or rejection of other microbes is determined by the original postpartum residents in the neonate.