Crucial nuances in understanding (mis)associations between the neonatal microbiome and Cesarean delivery. Issue 10 (October 2022)

• Record Type: Journal Article
• Authors: Sassin, Alexa M.; Johnson, Grace J.; Goulding, Alison N.; Aagaard, Kjersti M.
• Is Part Of: Trends in molecular medicine. Volume 28:Issue 10(2022)
• Page Start: 806
• Page End: 822
• Publication Date: 2022-10
• Subjects: microbiome -- vaginal seeding -- mode of delivery; Molecular biology -- Periodicals; Pathology, Molecular -- Periodicals; Physiology, Pathological -- Periodicals; 572.8
• DOI: 10.1016/j.molmed.2022.07.005
• Languages: English
• ISSNs: 1471-4914

Abstract

Abstract : As rates of Cesarean delivery and common non-communicable disorders (NCDs), such as obesity, metabolic disease, and atopy/asthma, have concomitantly increased in recent decades, investigators have attempted to discern a causal link. One line of research has led to a hypothesis that Cesarean birth disrupts the presumed normal process of colonization of the neonatal microbiome with vaginal microbes, yielding NCDs later in life. However, a direct link between a disrupted microbiota transfer at time of delivery and acute and/or chronic illness in infants born via Cesarean has not been causally established. Microbiota seeding from maternal vaginal or stool sources has been preliminarily evaluated as an intervention designed to compensate for the lack of (or limited) exposure to such sources among Cesarean-delivered neonates. However, to date, clinical trials have yet to show a clear health benefit with neonatal 'vaginal seeding' practices. Until the long-term effects of these microbiome alterations can be fully determined, it is paramount to conduct parallel meaningful and mechanistic-minded interrogations of the impact of clinically modifiable maternal, nutritional, or environmental exposure on the functional microbiome over the duration of pregnancy and lactation to determine their role in the mitigation of childhood and adult NCDs. Highlights: Increasing rates of Cesarean deliveries and common non-communicable disorders (NCDs) in children, such as obesity and metabolic disease, have resulted in attempts to uncover a causal link between the two. One line of research argues that being born via Cesarean rather than vaginal delivery detrimentally alters the neonatal microbiome in a way that could predispose the neonate to future NCDs. In general, the effect on the offspring microbiome is not durable and involves relative differences in only a few taxa. In addition, initial clinical trials have failed to show the effectiveness or reproducibility of vaginal seeding practices aimed at restoring the neonatal microbiome, although further trials are underway. Data on the effects of such practices on short- and long-term offspring health outcomes are needed. Only with a greater focus on the effects of maternal and fetal exposure during pregnancy and lactation will we discern true causal drivers of childhood and adult NCDs. In the USA, Cesarean delivery is rarely performed as a purely elective procedure upon maternal request. Access to medically indicated Cesarean delivery for situations of known maternal or fetal benefit are key to global efforts aimed at reducing health disparities and improving maternal and childhood morbidity and mortality.