The jury is still out on the existence of a placental microbiome

The human microbiome is crucial for regulating normal development, but the exact point when it is established remains unknown. A sterile placenta was traditionally considered a prerequisite for a healthy pregnancy, but studies have revealed that the placenta harbours microbial communities, even under normal conditions. However, reports have failed to provide evidence for the consistent presence of bacteria in the normal human placenta, challenging the in utero colonisation hypothesis. This mini review examines our understanding of the potential placental microbial colonisation in normal healthy pregnancies. This may impact the metabolic and immune functions of the growing foetus and have long-term consequences.

Automated summary

The human microbiome plays a crucial role in regulating normal development, but the timing of its establishment and colonization in the placenta remains unclear. Studies have shown microbial communities in the placenta even under normal conditions, impacting the metabolic and immune functions of the fetus with potential long-term consequences.