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Published on: November 16, 2016
The prenatal gut microbiome: are we colonized with bacteria in utero?
R W Walker1, J C Clemente2, I Peter2
1Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Insights
Maternal microbes are transmitted to infants, potentially before birth, influencing the infant gut microbiome and early health. This review explores evidence for prenatal microbial transfer and its implications.
Area of Science:
- Microbiology
- Immunology
- Neonatal Health
Background:
- Early-life gut microbial colonization is crucial for infant immune and metabolic development.
- Maternal microbes are transferred during childbirth, initiating infant gut colonization.
- Evidence suggests prenatal colonization may occur, with animal studies supporting in utero microbial transfer.
Purpose of the Study:
- To review existing evidence supporting in utero microbial transmission from mother to infant.
- To examine sources, mechanisms, and modifiers of prenatal microbial transfer.
- To highlight the importance of understanding early gut microbiome development.
Main Methods:
- Literature review of studies on maternal-infant microbial transmission.
- Analysis of evidence for prenatal microbial colonization in humans and animals.
- Discussion of physiological factors and microbiome modifiers.
Main Results:
- While maternal microbial transfer at birth is established, direct human evidence for in utero transfer is limited.
- Animal models and maternal physiological changes suggest prenatal transmission is plausible.
- Various factors can modify the maternal microbiome, potentially influencing infant colonization.
Conclusions:
- Confirming in utero microbial transfer in humans requires rigorous longitudinal birth studies.
- Understanding prenatal microbiome development is critical for infant health.
- Further research is needed to elucidate the timing and mechanisms of initial gut colonization.
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 foetal gut prior to birth, meaning that colonization could occur prenatally. Animal studies have shown that prenatal transmission of microbes to the foetus 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.
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