Definition

Meconium aspiration syndrome (MAS) is a set of symptoms that happen when an infant inhales meconium. Meconium is the first stool of an infant. It is sometimes passed into the fluid that surrounds the baby in the womb.

Causes

Not all infants who inhale meconium will have MAS. It is not known why some infants get MAS and others do not.

Risk Factors

Things that may raise a baby’s risk of meconium aspiration are:

• Delivery after 42 weeks
• Cesarean section delivery
• Abnormal heart rate during labor
• Low levels of amniotic fluid
• Low or high birth weight
• Meconium below the baby’s vocal cords

Things in a mother that may raise the chance of meconium aspiration in the baby are:

• High blood pressure
• Diabetes
• Respiratory disease
• Heart disease
• Smoking

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Symptoms

MAS may cause:

• Breathing that is too fast or too slow
• Blue skin color
• Grunting
• Nostrils that spread out when breathing
• Low muscle tone or muscle spasms

Diagnosis

This problem is diagnosed in a newborn based on symptoms and signs of meconium in the fluid. The diagnosis can be confirmed with a chest x-ray. Blood tests will also be done.

Treatment

The overall goal of treatment is to promote breathing. This can be done with:

• Intubation to open the airway and suction it as needed
• Oxygen therapy to ease breathing
• Breathing support in babies who cannot breathe on their own

Prevention

There are no methods to prevent MAS.