Meconium Aspiration Syndrome


Meconium is the first stool of an infant. Sometimes this stool is passed into the amniotic fluid that surrounds the baby in pregnancy.

Meconium aspiration is when the meconium is inhaled into the baby’s lungs. Meconium aspiration syndrome (MAS) is a set of symptoms that may result from meconium inhalation.


Not all infants who inhale meconium will develop these symptoms. It is not known why some infants develop MAS and others do not.

Risk Factors

Factors that may increase your baby’s risk of meconium aspiration include:

  • Post-term delivery—delivery after 42 weeks of pregnancy
  • Cesarean delivery
  • Abnormal heart rate during labor
  • Reduced amniotic fluid
  • Low or high birth weight
  • Meconium below the baby’s vocal cords
  • Low APGAR score after birth—assessment score of baby after birth

Factors in the mother that may increase the chance of meconium aspiration in the child include:

  • High blood pressure
  • Diabetes
  • Respiratory disease
  • Heart disease
  • Smoking
  • Heavily meconium stained amniotic fluid

Gestational Diabetes

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MAS may cause:

  • Breathing that is too rapid or too slow
  • Blue skin color due to lack of oxygen
  • Grunting
  • Nostrils that spread outward when breathing
  • Reduced muscle tone or spontaneous movement
  • A heart rate of less than 100 beats per minute


You will be asked about your baby's symptoms and medical history. A physical exam will be done. Tests may be ordered to look for complications or causes.

  • The doctor may need to see pictures of your baby’s chest. This can be done with:
    • Chest x-ray —to look for changes caused by meconium aspiration
    • Echocardiography —to look for changes in heart function caused by meconium aspiration
  • The doctor may also need to measure the level of oxygen in the blood. This can be done with:
    • Pulse oximetry
    • Blood tests


Meconium aspiration may not cause serious problems. Your doctor will monitor your baby. Other treatment may not be needed.

If your child is not vigorous in the delivery room the doctor may need to intubate your child to remove meconium from the trachea (breathing tube).

Supportive care may be needed if the aspiration is causing breathing difficulty. Your baby may need to be monitored in a neonatal intensive care unit (NICU).

Talk with your doctor about the best treatment plan. Options include:

Oxygen Therapy

MAS can lower the amount of oxygen to your baby’s body. Your baby may be given oxygen in the delivery room. The oxygen will be given through a mask or a hood that fits over the baby’s head. This will improve the amount of oxygen in the body by making more available in the lungs.

The therapy may be continued if your baby continues to have problems breathing.

Fluid Therapy

Your baby may be given IV fluids to control blood pressure and glucose levels.


Your baby may be given medication. The medication will coat the lungs and help clear the airways. This will also help your baby’s lungs mature.

Other medication may include antibiotics or heart medication. A special gas called nitric oxide may also be added. This gas can help open the blood vessels in the lungs. This will let more oxygen enter the body.

Support Care

In some cases, your baby may not be able to breathe properly on their own. Mechanical ventilation may be used to help your baby breathe.


Take these steps to help reduce your baby’s chance of MAS:

  • Manage chronic conditions. This includes high blood pressure, diabetes, respiratory disease, and heart disease.
  • If you smoke, talk to your doctor about how you can quit.


Healthy Children—American Academy of Pediatrics
Kids Health—Nemours Foundation


About Kids Health—The Hospital for Sick Children
Caring for Kids—Canadian Paediatric Society


Meconium aspiration. Kids Health—Nemours Foundation website. Available at:
...(Click grey area to select URL)
Updated October 2014. Accessed September 25, 2017.
Meconium aspiration. Lucile Packard Children’s Hospital website. Available at:
...(Click grey area to select URL)
Accessed September 25, 2017.
Meconium aspiration. University of Rochester Medical Center website. Available at:
...(Click grey area to select URL)
Accessed September 25, 2017.
Meconium aspiration syndrome. EBSCO DynaMed Plus website. Available at: http://www.dynamed... . Updated July 31, 2017. Accessed September 25, 2017.
Last reviewed September 2018 by EBSCO Medical Review Board Kari Kassir, MD
Last Updated: 9/30/2013

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