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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:

Gestational Diabetes
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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

Medication

Medicines that may be used are:

  • Antibiotics to treat infection
  • Surfactants to coat the lungs, clear the airways, and help the lungs mature
  • Nitric oxide gas to open blood vessels in the lungs to let more oxygen in the body

Prevention

There are no methods to prevent MAS.

RESOURCES

Healthy Children—American Academy of Pediatrics  https://www.healthychildren.org 

Kids Health—Nemours Foundation  http://kidshealth.org 

CANADIAN RESOURCES

About Kids Health—The Hospital for Sick Children  http://www.aboutkidshealth.ca 

Caring for Kids—Canadian Paediatric Society  http://www.caringforkids.cps.ca 

References

Chettri S, Bhat BV, et al. Current Concepts in the Management of Meconium Aspiration Syndrome. Indian J Pediatr. 2016 Oct;83(10):1125-1130.

Meconium aspiration. Kids Health—Nemours Foundation website. Available at: http://kidshealth.org/parent/medical/lungs/meconium.html. Updated November 2019. Accessed December 31, 2019.

Meconium aspiration syndrome. EBSCO DynaMed website. Available at:  https://www.dynamed.com/condition/meconium-aspiration-syndrome . Updated August 24, 2018. Accessed December 31, 2019.

Revision Information

  • Reviewer: EBSCO Medical Review Board Kari Kassir, MD
  • Review Date: 09/2019
  • Update Date: 05/29/2020