In recent years, some parents of newborns born via C-section have introduced a new, and controversial, step to the post-partum routine. Concerned about studies that show that babies delivered this way have lower levels of immune-boosting microbes, along with research that suggests that babies pick-up this good bacteria during their trip down the birth control, they are inserting gauze into the mother’s vagina during labor and swabbing it on the baby after delivery.
The process, known as “vaginal seeding,” is not one most doctors recommend. One study published earlier this year showed that this process might have some positive effect, but it was small—just 11 babies were involved—and only monitored the microbiome during the first month of life. Maria Dominguez-Bello, an associate professor of medicine at the New York University School of Medicine and author of the study, told NPR that while she is excited by the results so far, she encourages parents to hold off on taking matters into their own hands. For one, she would like to see the effect it has on children throughout early childhood and determine if it does, in fact, lead to fewer autoimmune disorders and allergies. More importantly, the D.I.Y. version may expose the newborn to dangerous bacteria; the mothers who participated in the study were all screened for pathogens and given antibiotics to avoid any potential adverse effects.
In case that’s not enough of a reason to stay away from vaginal seeding, new research is calling into question whether or not exposure to the birth canal’s microbiome makes much of a difference anyway. Writing for Stat, Sharon Begley looks at a recently published paper which claims that C-sections may be caused by an altered fetal microbiome in-vitro, rather than the method of delivery itself. In it, Dr. Kjersti Aagaard, a maternal-fetal medicine specialist at Baylor College of Medicine, scrutinizes the prior studies done on the connection between delivery methods and the microbiome and explains why he finds them unconvincing.
One issue with some of the studies on this topic is that they rest on the previously held assumption that fetuses are, bacterially speaking, blank slates before they leave the womb. Scientists now know that this is not the case, and that the microbiome is developed during gestation as well as delivery. Factors like maternal obesity or diabetes, which increase the likelihood of a C-section, may also result in an altered microbiome in-vitro. Studies show that a mom who eats poorly during pregnancy, as well as other factors associated with obesity and diabetes, will expose their fetuses to a less-healthy microbiome in-vitro than those who eat more healthily and gained less weight. Another issue is gestational age. Babies born via C-section are often preterm, and therefore may miss out on bacteria exposure by way of the placenta, which varies over the course of the nine months.
Most notably, no matter the cause of their altered microbiome, Aagaard found that any bacterial differences between babies born via C-section and vaginal delivery seem to disappear over time and have little long long-term effect on their health.
This news will hopefully provide some relief to the many mothers who experience grief or trauma after their C-section. In addition to the physical burden that the surgery presents, moms also contend with the emotional fallout that comes as a response to the widespread notion that having C-section is a personal failure and terrible for your child. This new research isn’t cause for doctors and midwifes to cease their efforts to lower the C-section rate, but it should make women feel much better if they had to have one.
