Meconium is the dark, thick and sticky first poop of a newborn baby. Meconium can be passed after a baby is born or while still in the womb. Swallowing some meconium is safe for your baby. Breathing in meconium can cause serious respiratory problems.


Blackish green, thick and tar-like meconium poop on a white diaper.
Meconium is the dark, thick and sticky first poop of a newborn baby. It's made of water, cells, hair, mucus and other materials.

What is meconium?

Meconium is your baby's first poop. It's darker and thicker than typical poop and extremely sticky. Meconium builds up inside your baby's intestines from swallowing amniotic fluid (the fluid that surrounds and cushions them inside your uterus). Ideally, your baby passes meconium shortly after birth. In some cases, babies will pass this substance before they are born. Swallowing meconium in the womb is not harmful, but breathing it in can cause serious complications.


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Is meconium in amniotic fluid bad?

It's OK if your baby swallows meconium before birth. The concern with meconium is that your baby will breathe it into their lungs. Aspirating or inhaling meconium can make it hard for your baby to breathe. This can lead to respiratory distress, infection or other serious conditions.

What is meconium staining?

Meconium staining is when your baby passes meconium before birth. Meconium-stained amniotic fluid is present in 12% to 20% of all deliveries. It's more common when you are beyond your due date. Stained amniotic fluid has a green or brown tint. Healthcare providers can recognize meconium-stained amniotic fluid and check your baby immediately after delivery for signs of respiratory issues.


How long does meconium last?

Your baby should pass their first poop within 24 to 48 hours after birth. Once your baby begins drinking colostrum (the first form of breastmilk) or formula, their digestive system will push the remaining meconium out. Most healthcare providers will ensure your baby's poop has begun changing to normal newborn poop. This means your baby's intestines are working correctly.


What does meconium do?

Meconium forms when your baby swallows amniotic fluid. As amniotic fluid passes through your baby's intestines, the water part of the amniotic fluid is absorbed. A sticky, tar-like substance is left behind. This debris is meconium and it lines your baby's large intestine. By the time your baby reaches full-term (40 weeks gestation), their intestines are filled with meconium. Passing meconium after birth shows that their digestive system is working.


What does it mean when my baby passes meconium?

Passing meconium after birth means your baby's digestive system and intestines are intact and working as they should. Your baby should pass meconium within two days of birth.

What happens if my baby doesn't pass meconium?

If your baby doesn't pass meconium within 48 hours, it may indicate a condition or disease. This could include:


What does meconium look like?

Meconium is thick and sticky. It resembles tar or sludge. Meconium is blackish green. Unlike normal poop, meconium doesn't smell.

What is meconium made of?

Meconium is made of water, cells, pee, hair, mucus and any other materials unborn babies swallow inside the womb.

Conditions and Disorders

Is swallowing meconium bad?

It's OK if your baby swallows meconium. When babies release meconium in the womb, it mixes with amniotic fluid. Swallowing this mixture is generally fine and doesn't cause issues.

How serious is inhaling meconium?

Meconium is thick and sticky. When this substance is breathed in or inhaled, it can fill your baby’s airways and make it hard for them to breathe. Aspirating or inhaling meconium into the lungs is called meconium aspiration syndrome (MAS). MAS can cause respiratory distress, infection and in rare cases, death.


How do doctors treat a baby who inhaled meconium?

If healthcare providers detect meconium in amniotic fluid, they will look for signs of fetal distress. Meconium is harmful when it's aspirated into your baby's lungs. Common signs of fetal distress include changes in heart rate and signs of respiratory problems like grunting, nasal flaring or blue skin color. Treatment is not necessary if your baby is active and crying.

If your baby has breathed in too much meconium and is unresponsive or in distress, your healthcare provider will suction your baby’s nose, mouth and throat. In more severe cases, providers may place a tube in your baby’s throat to further suction meconium from the windpipe. Finally, an oxygen mask can be placed on your baby’s face to help them breathe.

Additional Common Questions

Can inhaling meconium cause brain damage?

Inhaling or aspirating meconium can cause severe breathing problems. In some cases, a baby may need resuscitating after delivery. If your baby is oxygen-deprived for too long, it could lead to hypoxia. This is uncommon.

Can you test meconium for drugs?

Yes, meconium testing is a way to detect maternal alcohol, tobacco and drug use. Meconium testing can identify long term drug use (using drugs for weeks or months). It can be more accurate than urine drug tests.

When is a baby more likely to inhale meconium?

Your baby is more likely to aspirate meconium if your pregnancy goes beyond 40 weeks. When you’re overdue there is a higher chance that your baby will pass meconium while still in the womb.

A note from Cleveland Clinic

Meconium is your baby's first poop. It might look alarming, but it's normal for it to be dark, thick and sticky. Your baby should pass meconium within 48 hours of birth. Sometimes babies pass meconium while still inside the womb. They may swallow or breathe it in. Swallowing meconium is OK, but inhaling it into the lungs can cause serious problems. If this happens, your healthcare provider will check your baby for signs of respiratory problems. Most babies who breathe in meconium recover quickly and do not have any long term side effects.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 09/07/2022.

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