Meconium aspiration syndrome (MAS) occurs when a neonate inhales thick, particulate meconium. This is usually secondary to fetal hypoxia which causes increased peristalsis, relaxation of anal sphincters and reflex gasping. Most meconium deliveries involve some meconium staining of the liquor but the babies are vigorous, needing no further intervention.
This is a companion discussion topic for the original article at https://patient.info/doctor/paediatrics/meconium-aspiration