Baby's First Microbe

To study how babies develop their microbiomes — fetuses are thought to develop in a bacteria-free environment — Rob Knight and his colleagues characterized the microbiomes of babies delivered both vaginally and by Caesarean section using multiplexed 16S rRNA gene pyrosequencing. In PNAS, they report that vaginally delivered infants have microbial communities that are similar to their mothers' vaginal microbiota while C-section infants have microbial communities similar to skin microbiota — perhaps from the first person who held the infant, one of the researchers, Noah Fierer, tells the UK's Press Association. The authors write that this could "explain why susceptibility to certain pathogens is often higher in C-section than in vaginally delivered infants."