Meconium Aspiration Syndrome in Babies – Causes, Symptoms and Treatment by Dr. Srikanta J T

7 min read

Written by Dr. Srikanta J T

Dr. Srikanta J T

Dr Srikanta J.T is a Interventional Paediatric Pulmonologist based in Bangalore with 12+ years of experience.

His expertise lies in Paediatric Pulmonary Medicine, Paediatric Interventional P More

Meconium Aspiration Syndrome

A newborn baby is very delicate and vulnerable to many infections and dependent on the parents for every little thing. The parents also have a high level of curiosity to understand all the new things that happen with the arrival of the baby. Babies are always not all pleasant, the poop and the vomit, the very first faeces of the child are not something familiar to the parents. Apart from the routine, new babies can go through certain other uncomfortable situations too. This article discusses in depth about meconium aspiration syndrome in babies.

Meconium is a medical term that refers to the first stool or the faeces of the newborn. This stool is odourless than the regular ones as the baby only takes amniotic fluid as their intake. The regular stool is yellowish while meconium is green, thick dark and tar-like. Sometimes newborn babies can breathe a mixture of meconium and amniotic fluid into their lungs at the delivery time. Though not very common, this condition can happen.

In This Article

What is Meconium Aspiration Syndrome?

What is Meconium Aspiration Syndrome

Meconium refers to the first stool or faeces of the newborn. The MAS or the Meconium Aspiration Syndrome occurs when a newborn is over the due date and inhales a mixture of meconium and amniotic fluid in the lungs at the time of labour or in the womb. This syndrome can be a cause of acute illness and even death in a few newborns.

MAS is due to stress that the foetus undergoes, as a result of which it may pass stool on the womb. This stool is dark green in colour. Post-delivery, the infant will pass meconium stools for the initial few days as well. During delivery, under stress, this meconium mixes with the amniotic fluid which surrounds the foetus. The fetus can breathe this fluid mixture into the lungs before, during or after the birth causing Meconium Aspiration Syndrome.

Even though MAS is not fatal, it can lead to severe health issues for the newborn. And if not treated on time or left untreated can even lead to death.

Causes of Meconium Aspiration Syndrome in Babies

Causes of Meconium Aspiration Syndrome in Babies

MAS is the inhalation of the mixture of amniotic fluid and meconium by the foetus into their lungs. This can take place in the womb or during labour. The meconium is a dark green, thick, sticky, stool that has mucus and some intestinal secretions as well. The babies generally pass the first stool either after a few hours of birth or after a few days of birth. Due to destress during labour, the to-be born baby may inhale this mixture of amniotic fluid and faeces resulting in MAS.  MAS may lead to respiratory issues and even lead to severe complications or illness.

The Common reasons for the foetal distress and premature releasing of meconium are

  • A pregnancy that exceeds 40 weeks
  • Long-lasting or difficult labour
  • Health problems of the mother such as gestational diabetes or hypertension, heart ailments or chronic breathing disorder
  • Umbilical cord complications
  • Poor fetal growth due to some infection or problem
  • Smoking during pregnancy

The foetus will not produce meconium unless it is in the later stages of pregnancy. As the pregnancy advances to the date, the amount of amniotic fluid also keeps reducing. This can concentrate the meconium as well. Thus, MAS is common in newborn babies that are past 40 weeks. It is uncommon in preterm babies or otherwise.

[Read : Slow Fetal Growth During Pregnancy]

What Are The Symptoms of Meconium Aspiration Syndrome?

If the foetus expels meconium inside the womb, the signs and symptoms start to appear in the fetal stage. The infants who inhale meconium during labour show signs within a few hours after their birth. The most common symptom of MAS is respiratory disorder. The infant may either start breathing every heavily or start grunting during breathing. Many newborns can even stop breathing if the airways are blocked by the meconium.

Symptoms of MAS include

  • Respiratory distress
  • Low blood pressure
  • Bluish skin colour of the baby, also known as cyanosis
  • Limpness in the baby at the time of birth
  • Amniotic fluid with green colour streaks
  • Low heart rate before the birth of the baby
  • Low Apgar score of the baby (evaluation because of heart rate, skin colour, muscle tone, reflexes and breathing rate)
  • Breathing disorder (rapid, suspension or laboured breathing)
  • Breathing with a grunting sound
  • Pulling in of the chest wall
  • Yellow skin or nails due to long exposure to meconium

[Read : Know All About The Apgar Score In Newborns]

How is MAS Diagnosed?

Diagnosis of meconium aspiration syndrome in babies

MAS diagnosis takes place depending on the presence of meconium in the amniotic fluid. The doctor will diagnose MAS through the following steps

  • Observing the low heart rate of the foetus
  • Examining lung patches with a chest x-ray. This helps to find out if a material has entered the lungs of the newborn.
  • Blood gas test that helps to detect the low oxygen and carbon dioxide levels.
  • Assessing the abnormal breathing sound with the help of a stethoscope.

How is MAS Treated?

Any infant who is active, breathing normally and crying at the time of birth needs no treatment even with the presence of meconium in the amniotic fluid. It is however important to keep the baby under observation as MAS symptoms can appear within 24 hours.

The treatment of MAS depends on various factors, like the amount of inhaled meconium, the health of the newborn and the duration of exposure.

In case the newborn shows signs of MAS, like low heart rate, respiratory trouble, poor muscle tone, it must undergo these procedures.

1. Amnioinfusion

Amnioinfusion is good for babies who have a high risk of MAS due to very limited monitoring resources. A sterile liquid is injected into the amniotic fluid during delivery which helps in dissolving the meconium. It even reduces the inhaled amount of the fluid by the infant.

2. Respiratory Support

If the newborn cannot breathe or has a low heart rate, the doctor makes use of a bag and a mask and help them breathe, this will deliver oxygen to the baby and help in inflating the lungs.

3. For Babies With Acute MAS

The babies who have acute MAS symptoms must undergo the given procedures for better improvement.

  • Oxygen therapy to make sure there is sufficient oxygen in the blood.
  • Antibiotics such as ampicillin and gentamicin given intravenous to prevent or treat an infection.
  • Use of a ventilator (a breathing machine) to help your infant breathe.
  • Radiant warmer to keep the baby’s body temperature in the given range.
  • Chest physiotherapy to loosen the meconium trapped. The baby’s chest is tapped at regular periods.
  • ECMO or extracorporeal membrane oxygenation (ECMO) in case the baby does not respond to other procedures or has high blood pressure in the lungs.
  • Surfactant to help open up the lungs.

Can You Prevent Meconium Aspiration?

Early detection of MAS is the best way to prevent it. Getting monitoring of the foetus through ultrasonography and check-ups can help to assess if the baby is undergoing stress. The doctor can take the necessary steps to get rid of fetal suffering and pain at the time of labour. This even helps in reducing the chances of the development of Meconium Aspiration Syndrome or MAS.

In case the baby is experiencing stress, the doctor can assess and offer treatment to the baby immediately if there are any signs or indicators of MAS.

Here are some precautions you can take to avoid the potential risk of MAS

  • Get your check-ups and ultrasonography tests done in a diligent manner.
  • In case of health complications like diabetes, follow medications, treatment, and diet properly to reduce the risk of MAS during delivery.
  • Avoid smoking and drinking during pregnancy.
  • Consult your OBGYN if you see a green stain liquid during a water break.

What Complications Are Associated With Meconium Aspiration?

Complications Associated With Meconium Aspiration Syndrome

Most of the overdue newborns who have had MAS do not have long term health issues. Yet MAS is a serious issue and can impact the baby’s health.

  • If meconium reaches the lungs it can lead to infection as well as inflammation and there are high chances of a chronic lung disease etc.
  • Meconium can block the airways of the baby leading to lung being expanded. If this happens, the lungs can collapse or even rupture.
  • MAS can lead to an increase of the infant to develop a condition known as Pulmonary Hypertension of the Newborn known as PPHN. The high blood pressure in the vessels of the lungs of the infant can restrict the blood flow and make it difficult for the baby to breathe. This condition is rare but a fatal one.
  • Very rarely, severe conditions of MAS can limit the oxygen intake to the brain resulting in permanent brain damage.
  • Aspiration Pneumonia is one of the complications that can occur due to MAS.
  • Developmental issues like neurological disorders are also a possible complication for a newborn who has experienced MAS
  • On rare occasions, severe MAS may limit oxygen to the brain leading to permanent brain damage.

Meconium aspiration syndrome in babies is treatable with timely intervention and by taking all necessary precautions. Pregnant women with underlying health issues should undergo regular examination and testing, especially towards the delivery date. Most babies get back to their normal health within a few days post-delivery. Long-term complications are rare but a possibility.


1. Can Babies Survive Meconium Aspiration?

Yes, it is not difficult for the babies to survive meconium aspiration. If left untreated or not treated at time, the results are incurable. If the baby shows breathing disorder and abnormal chest X-ray with MAS, additional oxygen and medical assistance is a must.

2. Can Swallowing Meconium Cause Brain Damage?

Meconium is a cause as well as a sign of less oxygen. In the absence of careful management during labour and delivery or immediately after birth, it can lead to brain injury, cerebral palsy, and permanent disability. If the meconium does not clear from the airways or lungs of the baby, it can have severe consequences and can result in shortage of oxygen, brain injury, less oxygen and death before time.

Read Also: All You Should Know About Newborn Pee and Poop in the first 24 Hours After Birth

Dr. Srikanta J T, MBBS, Diploma in Child Health (DCH), Diplomate of National Board(DNB), Fellowship in Pediatric Pulmonology and Sleep Medicine(NUH, Singapore), Training in Interventional Pulmonology
Consultant - Paediatric Interventional Pulmonology, Allergy and Sleep Medicine, ASTER CMI Hospital
10 years of experience

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