what happens when a baby swallows poop in the womb?

Meconium Aspiration Syndrome Birth Injury
Meconium aspiration syndrome birth injury (MAS), sometimes referred to as neonatal aspiration of meconium, is a medical condition that affects newborns born with stool, called meconium, that has gotten into their lungs. If not detected and treated quickly, MAS can potentially lead to serious medical conditions,