National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Meconium aspiration syndrome


Other Names:
MAS
Categories:
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. This can cause breathing difficulties due to swelling (inflammation) in the baby's lungs after birth. Treatment may include suctioning the newborn's mouth as soon as the head emerges during delivery, deep suctioning of the windpipe, antibiotics to treat infection, oxygen to keep blood levels normal, and radiant heat to maintain body temperature. In severe cases, the baby may need assistance breathing (ventilator).[1]
Last updated: 1/12/2012

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Abnormal heart rate variability 0031860
Abnormal pulmonary thoracic imaging finding 0031983
Caesarian section 0011410
Fetal distress 0025116
Postterm pregnancy 0031169
Respiratory distress
Breathing difficulties
Difficulty breathing
[ more ] 		0002098
Transient pulmonary infiltrates 0005828
5%-29% of people have these symptoms
Aspiration pneumonia 0011951
Atelectasis
Partial or complete collapse of part or entire lung
0100750
Hypoxemia
Low blood oxygen level
0012418
Intrauterine growth retardation
Prenatal growth deficiency
Prenatal growth retardation
[ more ] 		0001511
Maternal diabetes
gestational diabetes
0009800
Maternal hypertension 0008071
Meconium stained amniotic fluid 0012420
Neonatal asphyxia 0012768
Pneumomediastinum 0025421
Pneumothorax
Collapsed lung
0002107
Premature rupture of membranes 0001788
Pulmonary arterial hypertension
Increased blood pressure in blood vessels of lungs
0002092
Wheezing 0030828
1%-4% of people have these symptoms
Encephalopathy 0001298
Pulmonary insufficiency 0010444
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Last updated: 7/1/2020
Meconium is the term used for the early feces passed by a newborn soon after birth. In some cases, the baby passes the meconium while still inside the uterus. This most often 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 immediately following birth. Some of the factors that may cause stress on the baby before birth include:[1]

  • Decreased oxygen immediately before or during the birthing process 
  • Difficult or lengthy labor and delivery 
  • Delivery that occurs past the due date
  • High blood pressure in the pregnant mother
  • Diabetes in the pregnant mother
Last updated: 1/12/2012

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Meconium aspiration syndrome. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The Merck Manuals Online Medical Library provides information on this condition for patients and caregivers. 

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Meconium aspiration syndrome. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • My son has suffered meconium aspiration syndrome. What causes this condition? See answer


  1. Lee KG. Meconium aspiration syndrome. MedlinePlus. 2009; http://www.nlm.nih.gov/medlineplus/ency/article/001596.htm. Accessed 1/12/2012.