This blog was medically reviewed by Annie Alwine, MD, staff neonatologist at Children’s Minnesota.
As a new parent, you may feel excited about many things and worried about many things – and that’s very normal! You may have heard of meconium aspiration syndrome and it can sound scary for new parents. But, understanding it can help you feel more prepared. In this guide, you’ll learn what it is, what symptoms to watch for and how it’s treated so you can feel more confident if concerns come up.
Before or during birth, some babies pass their first bowel movement, called meconium, into the amniotic fluid. In some cases, a baby may breathe this fluid into their lungs. This is called meconium aspiration syndrome (MAS). This blog explains what MAS is, common symptoms, causes, and how doctors diagnose and treat it to help babies recover quickly and safely.
Learn more about expert newborn care in our neonatal program.
What is meconium?
Meconium is a thick, sticky and dark substance that forms the infant’s first stool. Most babies pass meconium after birth, usually within the first day or two.
Sometimes, a baby passes meconium before or during labor. When this happens, it can mix with the amniotic fluid. This can become a concern if the baby breathes that fluid into their lungs.
What is meconium aspiration syndrome?
Meconium aspiration syndrome (MAS) happens when a newborn breathes in amniotic fluid that contains meconium. MAS, sometimes called neonatal aspiration of meconium, can occur before, during or right after birth.
When meconium enters the lungs, it can block airways, irritate lung tissue and make it harder for the baby to breathe. Some babies have mild symptoms, while others need more support right after birth.
Meconium aspiration symptoms
Babies with MAS may show signs of breathing trouble soon after birth. These symptoms can range from mild to severe depending on the situation.
Common signs include:
- Fast or difficulty breathing
- Grunting or noisy breathing
- Bluish skin (especially around the mouth)
- Low energy or weak crying
- Chest retractions (skin pulling in along the ribs with breaths)
- Low oxygen levels
- Yellow-green staining on the skin, nails or umbilical cord
Our NICUs are fully equipped to treat the littlest babies with the most critical needs.
Causes and risk factors
There are several reasons why a baby may pass meconium before birth and be at risk for MAS. Stress on the baby before or during delivery is the most common cause of early passage of meconium. “Fetal distress” or stress on the infant is caused by low oxygen and/or blood flow to the baby. Stress can also cause a fetus/baby to take gasping breaths, which can lead to inhalation of amniotic fluid mixed with meconium. There are several risk factors that can cause stress on the infant before or during birth.
Meconium aspiration risk factors
- Late pregnancy/overdue baby
- Long or difficult labor
- Pregnant person having high blood pressure or preeclampsia
- Pregnant person having diabetes
- Smoking during pregnancy
- Infection during pregnancy
Meconium aspiration syndrome diagnosis
Your care team usually diagnoses MAS soon after birth based on symptoms and the baby’s appearance. They may notice breathing problems or see meconium-staining during delivery. To confirm the diagnosis, providers may use chest X-rays to look at the lungs and blood tests to check oxygen levels. An early diagnosis can help guide your care team’s next steps for treatment and recovery.
Meconium aspiration syndrome treatment
The treatment for MAS depends on how severe the baby’s symptoms are. Some babies only need extra oxygen and close monitoring to help, and some babies may need more support than that.
More serious cases of MAS may involve the baby needing help with breathing using a ventilator, which is a machine to help your child breathe. In rare cases, even more support may be needed, like extracorporeal membrane oxygenation (ECMO). ECMO may be used to give the lungs time to heal.
Children’s Minnesota offers specialized newborn care, including advanced breathing support when needed. Learn more about ECMO and what conditions may benefit from it, including meconium aspiration syndrome.
Complications of meconium aspiration
Most babies recover from MAS well with proper care, but some may have complications. These complications can include lung infections, inflammation or difficulty getting enough oxygen.
In rare cases, MAS can lead to persistent pulmonary hypertension, a condition that decreases blood flow to the lungs. But early treatment can greatly lower the risk of serious complications of MAS.
Meconium Aspiration FAQs
How common is meconium aspiration?
Meconium-stained amniotic fluid happens in about 10-20% of births. However, only a smaller number of babies develop meconium aspiration syndrome. It is more common in babies born past their due date or in stressful deliveries.
Can a baby die from inhaling meconium?
Severe cases of MAS can be life-threatening, but most babies recover with proper monitoring, treatment and care. The baby’s survival rate depends on how quickly the condition is treated and how severe it is.
How long does a baby stay in the NICU after meconium aspiration?
Many people wonder, after meconium aspiration, how long will my baby be in the NICU? After meconium aspiration, the baby’s NICU stay can vary. Some babies go home within a few days, while others may need a longer stay if they need breathing support or ECMO. The timeline of a NICU stay depends on how quickly the baby improves and responds to treatment.
How the experts at Children’s Minnesota can help
Meconium aspiration syndrome can feel scary, but expert care can make a big difference. At Children’s Minnesota, our neonatal specialists are experts in diagnosing and treating breathing conditions in newborns.
We use advanced tools to monitor your baby closely and provide the right level of support — from oxygen therapy to specialized treatments when needed. Our goal is to help every baby breathe easier and recover safely.
If your baby needs extra care at birth, our neonatal program offers compassionate, family-centered support every step of the way. You can trust our team to guide you and answer your questions during this important time.
The neonatology program at Children’s Minnesota has the advanced treatment your baby needs.
