The prenatal gut microbiome: are we colonized with bacteria in utero?

Abstract

The colonization of the gut with microbes in early life is critical to the developing newborn immune system, metabolic function and potentially future health. Maternal microbes are transmitted to offspring during childbirth, representing a key step in the colonization of the infant gut. Studies of infant meconium suggest that bacteria are present in the fetal gut prior to birth, meaning that colonization could occur prenatally. Animal studies have shown that prenatal transmission of microbes to the fetus is possible and physiological changes observed in pregnant mothers indicate that in utero transfer is likely in humans as well. However, direct evidence of in utero transfer of bacteria in humans is lacking. Understanding the timing and mechanisms involved in the first colonization of the human gut is critical to a comprehensive understanding of the early life gut microbiome. This review will discuss the evidence supporting in utero transmission of microbes from mother to infants. We also review sources of transferred bacteria, physiological mechanisms of transfer and modifiers of maternal microbiomes and their potential role in early life infant health. Well-designed longitudinal birth studies that account for established modifiers of the gut microbiome are challenging, but will be necessary to confirm in utero transfer and further our knowledge of the prenatal microbiome.

Meconium‐stained amniotic fluid as a protective factor against childhood dermatitis and skin rash‐related hospitalization in the offspring – a population‐based cohort analysis

“…2 A healthy intestinal microbiome is characterized by microbial diversity, and by the presence of microbiota that has been found to augment metabolism, decrease susceptibility to infection, inflammatory and autoimmune conditions, enhance cancer resistance and influence brain function. 2 The microbiome's assembly thought by many to begin at birth is known to be influenced by mode of delivery, type of feeding and use of antibiotics. 2 The microbiome's assembly thought by many to begin at birth is known to be influenced by mode of delivery, type of feeding and use of antibiotics.…”

Maternal antibiotic use and child asthma: is the association causal?

“…Maternal microbiota and metabolites in utero may help train the fetal innate immune system and have been causally implicated in allergic airway disease in mice [13,14]. When used at or after birth, antibiotics may disrupt mother-to-newborn transmission of healthy microbiota of the maternal gut, vagina, skin and/or breast milk [15,16]. In addition to effects on the microbiome and metabolome, antibiotics may alter epigenetics [17] and fetal development [18].…”

Relationship Between Oligosaccharides and Glycoconjugates Content in Human Milk and the Development of the Gut Barrier

“…An essential part of the development of immunity and barrier function is the healthy development of an individual's microbiota. The neonatal gut colonization has been suggested to occur by different mechanisms: early colonization in utero (Walker, Clemente, Peter, & Loos, ), entero‐mammary route of transmission (Jost, Lacroix, Braegger, Rochat, & Chassard, ), and, maternal skin/infant oral cavity flow back during lactation (Biagi et al., ; Ramsay, Kent, Owens, & Hartmann, ).…”

“…The initial colonization of the surfaces of infant respiratory, urinary and gut mucosa starts, according to recent insights, in utero (Collado, Rautava, Aakko, Isolauri, & Salminen, ; Perez‐Muñoz, Arrieta, Ramer‐Tait, & Walter, ; Walker et al., ). This process occurs mostly in the last stage of pregnancy (Donnet‐Hughes et al., ; Rodriguez, ).…”