Previous studies have shown that gut microbiota in infancy could affect neurodevelopment, and infants delivered by cesarean are not exposed to potentially helpful microbes acquired by infants during vaginal delivery, wrote Lepeng Zhou, MD, of Southern Medical University, Guangdong, China, and colleagues.
“Infants delivered by C-section start life with very different bacteria than those born vaginally,” corresponding author Jose Clemente, PhD, of Icahn School of Medicine at Mount Sinai, New York, said in an interview. “Because this is the first time the newborn is exposed to microbes, we and others have hypothesized for some time that this ‘first encounter’ might be significant to shape the development of the baby,” he said.
“A few years ago, we demonstrated that it is possible to change the microbiome of C-section–delivered infants using an intervention that makes their microbiome more similar to that of a vaginally-delivered infant,” Dr. Clemente told this news organization. “In this study just published, we show that this procedure not only changes the microbiome of C-section infants, but it also modifies a health outcome (in this case, neurodevelopment). This is highly significant because it opens the way to reduce the risk that C-section infants have for certain conditions through a very simple microbial intervention,” he said.
‘Significantly higher’ ASQ-3 scores
In the current study, published in Cell Host & Microbe, the researchers examined the impact of vaginal microbiota transfer (VMT) on the neurodevelopment of cesarean-delivered infants. They randomized 35 women scheduled for cesarean delivery with a single infant to VMT and 41 to a control intervention of saline gauze for their infants immediately after delivery.
The primary outcome of infant neurodevelopment was assessed using the Ages and Stages Questionnaire (ASQ-3) score at 6 months. The researchers also collected fecal samples and assessed safety outcomes for the infants at 3, 7, 30, and 42 days after birth. The final analysis comprised 32 infants in the VMT group and 36 in the control group. The mean age of the mothers was 32 years; the mean gestational age of the infants was 39 weeks, but the difference was significant and slightly less in the VMT group compared with the controls (38.38 weeks vs. 39.13 weeks, P = .007). A group of 33 vaginally-delivered infants (VD) underwent ASQ-3 testing to serve as a reference group.
At 6 months, ASQ-3 scores were significantly higher (10.09%, P = .014) with VMT compared with controls, and the difference remained significant after adjustment for multiple factors including gestational age.
ASQ-3 total scores at 6 months were not significantly different between the VMT group and the VD reference group (mean difference of 8.84 VMT to VD, P = .346); scores between these groups also were similar at 3 months (mean difference of –1.48 VMT to VD, P = .900) and no significant differences appeared in ASQ-3 subdomains between these groups at either time period.
An examination of gut metabolites in stool showed significant differences in fecal metabolites and metabolic function, signs of gut microbiota maturation, the researchers noted.
“Interestingly, all the genera and metabolites that exhibited positive correlations with neurodevelopmental scores were upregulated in the VMT group, whereas the only negative correlation of Klebsiella was downregulated, indicating that VMT may impact neurodevelopment through the modulation of specific gut microbial genera and metabolites,” the researchers wrote.
No serious adverse events occurred in either group during the study period. Nine adverse events were reported; 4 in the VMT group and 5 in the control group. The most common AEs were mild skin disorders, including papules, pustules, and erythema.
The findings were limited by several factors including the potential for transfer not only of vaginal microbiota, but also vaginal metabolites, mycobiome, and virome, which blurs the potential mechanism of VMT, the researchers noted. Other limitations were the relatively short study period, small sample size, and cervical HPV screening within the past 5 years, not during pregnancy, they wrote.
However, the results suggest that VMT is safe, and may help improve the fecal microbiome in cesarean-delivered infants, and the long-term effects merit further studies in larger populations, they concluded.