Meconium aspiration syndrome, or MAS, occurs when a newborn inhales meconium into its respiratory system. Meconium is a thick, sticky substance found in the intestines of a fetus or newborn.
Meconium may be released into the amniotic fluid when a fetus is in distress. This may occur when a fetus is not getting enough oxygen or nutrients. If this happens, the amniotic fluid surrounding the fetus goes from clear to green. As a newborn takes his or her first breath, or aspiration, the meconium can be inhaled into the lungs. It may partly or completely block the airways. This keeps the baby from getting enough oxygen.
In developed countries, 8% to 20% of the babies born after 34 weeks gestation have meconium-stained amniotic fluid. As many as 1% to 9% of these babies develop meconium aspiration syndrome. MAS is a leading cause of serious illness and death among newborns.
Following are some of the factors that increase the risk of meconium aspiration syndrome: