Complex sentence: Meconium aspiration syndrome (MAS, alternatively "Neonatal aspiration of meconium") occurs when infants take meconium into their lungs during or before delivery.
Split into simpler sentences: Meconium aspiration syndrome (MAS, alternatively "Neonatal aspiration of meconium") is a medical condition affecting newborn infants. It occurs when meconium is present in their lungs during or before delivery.