Infants may not be so sterile, as some researchers are now finding that fetuses may be seeded with bacteria during pregnancy, writes Carl Zimmer at the New York Times.
Initially, infants were thought to obtain their microbiota during birth and afterward. But a few years ago, Zimmer notes, researchers began to see hints that that may not be the case. For example, he writes that Esther Jiménez Quintana from Complutense University of Madrid and her colleagues uncovered bacteria in the amniotic fluid, placenta, and umbilical cord blood of healthy infants while the University of Florida's Josef Neu and his team found that newborn's stool contained a plethora of bacteria.
Though how the microbiome develops is unknown, researchers like Neu are examining how it affects fetuses and how it could be altered to prevent early labor or to boost the immune system of the baby after birth, Zimmer adds.