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.
Not all infants who inhale meconium will have MAS. It is not known why some infants get MAS and others do not.
Things that may raise a baby’s risk of meconium aspiration are:
Things in a mother that may raise the chance of meconium aspiration in the baby are:
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MAS may cause:
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.
The overall goal of treatment is to promote breathing. This can be done with:
Medicines that may be used are:
There are no methods to prevent MAS.
Healthy Children—American Academy of Pediatrics
Kids Health—Nemours Foundation
About Kids Health—The Hospital for Sick Children
Caring for Kids—Canadian Paediatric Society
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:
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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.
Last reviewed September 2019 by
EBSCO Medical Review Board
Kari Kassir, MD
Last Updated: 5/29/2020