Researchers are reporting that the lungs and placentas of fetuses in the womb—as young as 11 weeks after conception—already show a bacterial microbiome signature, which suggests that bacteria may colonize lungs well before birth. This first-time finding deepens the mystery of how the microbes or microbial products reach those organs before birth and what role they play in normal lung and immune system development.
The researchers found that a human fetal microbiome DNA signature is present in lungs as early as the first trimester. This fetal lung microbiome showed changes in diversity during fetal development, suggesting microbiome maturation with advancing gestational age. The study, funded by NHLBI, appeared in the American Journal of Respiratory and Critical Care Medicine.