Whether a developing baby (the fetus) has a microbiome or whether it is sterile during pregnancy and only gets "seeded" by microbes from the mother during birth is still being hotly debated. For years it was thought that the fetus and placenta were sterile (no microbes), but then several studies said there is evidence for the fetus and placenta having a microbiome (community of microbes).
Recently an international group of researchers stated that NO, there is no fetal microbiome. They reviewed current evidence, and according to their opinion - a healthy fetus is sterile. Instead, they suggest that the microbes some researchers found were due to contamination when the samples were taken or during analysis.
We'll see how this all develops. Science is always evolving, with new findings, and lots of debate and controversy.
From Medical Xpress: Expert analysis refutes claims that humans are colonized by bacteria before birth
Scientific claims that babies harbor live bacteria while still in the womb are inaccurate, and may have impeded research progress, according to University College Cork (UCC) researchers at APC Microbiome Ireland, a world-leading Science Foundation Ireland (SFI) Research Center, which led a perspective published today in the journal Nature. ...continue reading "Group of Researchers Claim That the Fetus Does Not Have A Microbiome"