The childbirth delivery method can have a powerful and pervasive impact on the gut microbiome development of a newborn baby throughout infancy. The prevalent thinking is that the early intestinal microbiome provides essential stimuli for the baby’s budding immune system. In other words, the microorganisms that cultivate the baby’s intestine during and after childbirth may influence long-term colonization and immune development, and therefore the emergence of diseases later in life.
A baby gets a “dose” of healthy microflora when it passes through the birth canal. Lactobacillus acidophilus is the predominant species of bacteria that populate the vagina. As the pregnancy comes to term, the mother’s body begins to increase the number of healthy vaginal bacteria, especially Lactobacillus acidophilus, with the intent of transferring it to the baby. This is nature’s way of developing healthy microbiomes in the next generation.
Surgically delivered babies do not receive this inoculation. Their first exposure to healthy bacteria comes from exposure to the mother’s skin. In addition, they pick up small quantities of microbes from the doctors and nursing staff.
In a study that compared the amounts of hospital-acquired bacteria in the guts of newborns, hospital-acquired bacteria were present in around 80 percent of babies born by C-section. Interestingly, hospital-acquired bacteria formed around 30 percent of their total microbiome. Comparatively, this number was only 10 percent in vaginally born babies.
The researchers also saw that the amount of maternal-origin beneficial bacteria belonging to the phylum Bacteroides was lesser in C-section babies. There were more opportunistic pathogens such as the Enterococcus, Klebsiella, and Enterobacter species. When the babies weaned between 6 to 9 months of age, these differences had shrunk. In a different study, C-section delivery was associated with delayed colonization of Bacteroides and a lower microbial diversity overall.
Surprisingly, the babies’ gut bacteria seem to have originated from their mother’s guts rather than the birth canal. This suggests that at least some of the microorganisms collected by vaginal-birth babies might come from around the anus as well. This revelation puts less value on the much-debated practice of “vaginal seeding,” in which a vaginal swab from a woman who delivers by C-section is rubbed over the baby’s face and body, to replicate the collection of microflora from the birth canal as it happens during vaginal birth.
More studies are needed to consolidate the differences in mode of birth for long-term impact on the gut and overall health. How they correlate with diet and nutrition interventions designed to boost a healthy gut throughout childhood also needs to be assessed. The early findings regarding probiotics supplementation for C-section babies, particularly breastfed ones, seems promising.