Experts debunk scientific claims that human babies are colonized by bacteria prior to birth

Experts debunk scientific claims that human babies are colonized by bacteria prior to birth ...

A group of experts unanimously rejected the notion of a fetal microbiome and concluded that the discovery of microbiomes in fetal tissues was caused by the contamination of urine samples taken during vaginal delivery, medical procedures, or laboratory testing.

Leading experts from a variety of scientific disciplines have discovered flaws in research that support the existence of a "fetal microbiome."

According to University College Cork (UCC) researchers at APC Microbiome Ireland, a world-leading Science Foundation Ireland (SFI) research centre, the findings published today (January 25, 2023) in the prestigious scientific journal Nature.

If true, previous assertions that the human placenta and amniotic fluid are normally colonized by bacteria would have serious implications for clinical medicine and pediatrics, as well as established principles in immunology and reproductive biology.

Prof. Jens Walter, UCC and APC's principal investigator, assembled a cross-disciplinary team of 46 leading experts from around the world to investigate the evidence for microbes in human fetuses.

Professor Jens Walter, the Principal Investigator at University College Cork and APC Microbiome Ireland, has assembled a cross-disciplinary team of 46 leading experts from around the world to investigate the evidence for microbes in human fetuses. Credit: UCC

The research team unanimously rejected the notion of a fetal microbiome and concluded that contamination of womb samples was caused by contamination during vaginal delivery, clinical procedures, or during laboratory analysis.

International experts encourage researchers to focus their studies on mothers' microbiomes and newborn infants' microbiomes, which prepare the foetus for post-natal existence in a microbial world, in the Nature article.

Prof. Walter: "This consensus gives direction for the field in its pursuit of advancement and allows researchers to concentrate on the areas that will be most effective." Knowing that the fetus is in a sterile environment, it implies that colonization by bacteria occurs during pregnancy and early post-natal life, which is where therapeutic research on the microbiome should be focused."

Expert international authors offer suggestions on how scientists may avoid contamination hazards in the future when performing analyses of other samples where microbes are likely to be absent or present at low levels, such as internal organs and tissues within the human body.

Nature, 25 January 2023, Reference: "Questioning the fetal microbiome and the pitfalls of low-biomass microbial studies"

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