When does microbial life begin? Many experts assert that the vast underworld of bacteria take up residence as life emerges from the womb.
That is the prevailing thought and also the rationale for vaginal delivery as the healthiest start for new babies. But new evidence is shaking up that theory. Metagenomic sequencing suggests the growing fetus may also be privy to a rich soup of microbes in the placenta. These may offer vital contributions to metabolism and immunity in the rapidly growing organism.
On the other hand, these microbes may let loose deviant metabolites which could harm fetal brain development which could extend throughout life. A review in Pediatric Research by Joann Romano-Keeler and Jörn-Hendrik Weitkamp discusses the current literature on microbial colonization in the fetus and how normal gut microbes produce a healthy neonatal mucosal immune system. Also it reveals how dysbiosis can lead to compromised immune function throughout life.
Maternal genetics, diet, medications and probiotics all play key roles in the fetal microbiome.
The field of probiotics keeps getting more interesting.