Meconium aspiration syndrome is a serious condition in which a newborn breathes a mixture of meconium and amniotic fluid into the lungs around the time of delivery.

Meconium is the term used for the early feces (stool) passed by a newborn soon after birth, before the baby has started to digest breast milk (or formula).

In some cases, the baby passes stools (meconium) while still inside the uterus. This usually happens when babies are under stress because they are not getting enough blood and oxygen.

Once the meconium has passed into the surrounding amniotic fluid, the baby may breathe meconium into the lungs. This may happen while the baby is still in the uterus, or still covered by amniotic fluid after birth. The meconium can also block the infant's airways right after birth.

This condition is called meconium aspiration. It can cause breathing difficulties due to swelling (inflammation) in the baby's lungs after birth.

Risk factors that may cause stress on the baby before birth include:

• Decreased oxygen to the infant while in the uterus
• Diabetes in the pregnant mother
• Difficult delivery or long labor
• High blood pressure in the pregnant mother
• Passing the due date