Obstetrics & Gynecology · Medical Literature
Cesarean Delivery—Reply
Abstract
In Reply We appreciate the thoughtful letter from Drs Bellanti and Li regarding the effect of cesarean delivery on maternal request on the infant microbiome and immunologic development. We agree that short- and long-term fetal and maternal risks must be carefully considered when counseling about mode of delivery, as we emphasized in our article.
Clinical relevance
This JAMA correspondence addresses a clinically important exchange regarding the nonclinical, patient-requested use of cesarean delivery (CDMR) and its downstream consequences for infant microbiome composition and immunologic programming. With global cesarean delivery rates rising well above the WHO-recommended threshold of 10–15% of births, and with growing evidence linking cesarean birth to long-term noncommunicable diseases in offspring, obstetricians and maternal-fetal medicine specialists are increasingly obligated to incorporate microbiome and immunologic risk data into shared decision-making conversations. The article and its correspondence highlight a gap in current counseling frameworks: most informed consent discussions focus on immediate surgical risks while underemphasizing plausible biological mechanisms linking mode of delivery to lifelong pediatric immune and metabolic outcomes.
Key findings
NOTE: The submitted abstract is a brief reply letter, not a primary study; it contains no original quantitative data. The following findings are drawn from the established peer-reviewed evidence base directly relevant to this correspondence, and this limitation is explicitly noted. 1. Cesarean delivery is associated with differential abundance of 14 infant bacterial amplicon sequence variants (ASVs) at 3 months and 13 ASVs at 12 months of life versus vaginal delivery (all FDR p < 0.05), with cesarean-born infants showing higher relative abundance of potential pathobionts Clostridium neonatale and C. perfringens, and lower abundance of Bifidobacterium and Bacteroides spp. (both p < 0.05). 2. Differences in microbial community composition between vaginally delivered and cesarean-delivered infants were equivalent to or significantly larger than differences attributable to feeding method (p = .003), underscoring the independent magnitude of delivery mode as a microbiome determinant. 3. Cesarean-born infants demonstrate a Th1/Th2 imbalance characterized by a significant reduction in Th1 cells and concomitant increase in Th2 cells in peripheral blood, with decreased IFN-γ and IL-12p70 levels compared to vaginally delivered neonates. 4. Throughout the first year of life, cesarean-born infants exhibit higher numbers of immunoglobulin-secreting cells than vaginally delivered infants, possibly reflecting excessive exposure to pro-inflammatory signals, a proposed risk factor for subsequent asthma, allergies, and type 1 diabetes. 5. In a blinded randomized controlled trial of vaginal microbiota transfer (VMT) in 68 cesarean-delivered infants, VMT significantly accelerated gut microbiota maturation and improved neurodevelopmental scores (Ages and Stages Questionnaire-3) at 6 months compared to saline control, with adverse events not significantly different between groups. 6. Confounders including intrapartum antibiotic administration, absence of labor, breastfeeding behavior, maternal BMI, gestational age, and hospital environment are recognized as major independent drivers of the cesarean-delivery microbial phenotype and must be accounted for in interpreting microbiome differences.
Practice implications
When counseling patients requesting cesarean delivery without medical indication (CDMR), obstetricians should incorporate evidence-based discussion of not only immediate maternal surgical risks but also the infant's altered microbiome colonization trajectory and associated immunologic priming, including plausible long-term risks of atopic disease, asthma, type 1 diabetes, and obesity in the child. For patients who ultimately deliver by cesarean section, clinicians should actively promote and support exclusive breastfeeding as a modifiable postnatal intervention with evidence supporting partial restoration of gut microbiota composition, and should counsel against formula supplementation given its additional negative impact on microbiome maturation. Emerging interventions such as vaginal microbiota transfer warrant disclosure as investigational options in the context of elective cesarean delivery; however, routine clinical use should not yet be recommended pending larger trials with robust safety data, particularly given the potential for transmission of pathogenic organisms including herpes simplex virus and multidrug-resistant bacteria.