Preterm infants with severe intrauterine inflammation acquire bacteria and form gut microbiome in utero by drinking contaminated amniotic fluid.

(goals) In this study, we examined the association between microbiome of placenta or gastric juice at birth and first meconium to clarify the pathway of gut microbiota acquisition in preterm infants. (conclusion) The microbiome of gastric juice and meconium were similar in preterm infants exposed severe inflammation in utero. These results suggest that swallowing contaminated amniotic fluid in utero with severe inflammation leads to the formation of gut microbiome in preterm infants.