Meconium – What Is It? 9 Things You Need To Know

Let’s face it, newborn babies poop a lot in the first few days and weeks of life.

Your baby’s first bowel movement after birth is called meconium.

If you’re not expecting it, meconium can come as quite a surprise.

What is meconium?

Meconium is a sticky substance with a consistency similar to tar. For Australian and British readers, think Vegemite or Marmite!

It lines your baby’s intestines and helps keep the large intestine open as your baby is growing in the womb.

Here are 9 things you need to know, to help prepare yourself for the sticky stuff.

#1: It’s super sticky

Meconium is surprisingly sticky, which can make it difficult to remove from your newborn’s delicate skin.

Some swear by this simple little trick to make clean up easier. Try applying a thin layer of olive oil (or similar) to your baby’s diaper area before putting on a clean nappy. This acts as a lubricant, so when the meconium hits, it’s easy to wipe off.

#2: Meconium is more than just poop

In pregnancy, from around 14 weeks, your baby regularly swallows amniotic fluid. The amniotic fluid contains mucus, baby’s hair (lanugo), intestinal cells, bile, and water.

The amniotic fluid passes through the baby’s small intestine, which removes and absorbs water. Any debris left behind is passed to the large bowel.

This builds up and forms a sludgy tar-like substance. By the time the baby is full-term, meconium has filled most of the intestine.

#3: It’s greenish-black in color

The thick sludgy substance is dark green or black in color and can look alarming as you open the nappy.

But don’t worry – it’s completely normal for it to be this color.

In the days after birth, your breasts produce a substance called colostrum. Colostrum has many positive benefits, including a natural laxative effect. It helps meconium move from the bowel.

In a healthy full-term baby this usually happens within the first 12-24 hours after birth. It can sometimes happen even before the baby has had the first feed – so be prepared!

If your newborn hasn’t done a poo within the first 48 hours, your doctor might want to check for an obstructed bowel.

#4: Meconium is sterile

The good news: although it might look pretty gross, meconium is actually sterile until after birth. That means it doesn’t contain bacteria.

This is partly what makes it different from the poo babies pass once they begin to digest milk. It’s also the reason why meconium poops have no smell.

#5: Meconium only lasts a few days

You’ll be pleased to know meconium doesn’t last forever. Most breastfed babies will only pass meconium for a few days before their stool begins to change.

As colostrum changes to milk and your baby begins to ingest greater volumes, you’ll soon find your baby passes all the meconium in her system.

#6: Poop changes color

It’s a really positive sign when you start seeing changes in your baby’s stool (I bet that’s something you didn’t think you’d be celebrating)

A change in the color of your baby’s poo shows she has passed all the meconium and is getting what she needs from milk.

#7: Babies can release meconium in the womb

Babies will typically pass their first stool within 12-24 hours. Sometimes, though, a baby will have a bowel movement prior to birth.

The meconium and amniotic fluid mix together and surround your baby. This is known as meconium staining.

If a baby passes meconium during labor and the amniotic sac has broken, the amniotic fluid will appear greenish or brown.

The baby can become covered in meconium, especially if there’s lots of vernix (the waxy coating on the skin). The baby may swallow (not to be confused with inhale or aspirate) the meconium; this won’t do any harm.

If the mother’s waters break during labor and meconium is noticed, care providers might become concerned about the health of your baby.

Meconium in amniotic fluid is potentially a sign of fetal distress.

#8: Overdue babies are more likely to pass meconium in labor

Babies sometimes have a bowel movement before birth because their digestive systems have matured, which means they’re ready for life outside the womb.

It’s more likely babies will pass meconium before birth if the pregnancy goes beyond the estimated due date. It’s rare for meconium to be passed earlier than 34 weeks gestation.

Research shows meconium-stained amniotic fluid (MSAF) happens in 12-16% of all births, and is more common after 40 weeks. Approximately 30% of babies born at 40 weeks and nearly half of babies born after 42 weeks will have MSAF.

#9: Meconium can be problematic if inhaled- Meconium Aspiration Syndrome (MAS)

The main concern when babies have obviously passed meconium in amniotic fluid before or during labor is they might inhale the fluid into their lungs. This is known as meconium aspiration syndrome (MAS).

If the meconium is inhaled (rather than swallowed), it can partially or completely block the airways causing respiratory distress (breathing problems).

Babies with this condition will often need to be admitted to the special care baby unit for additional monitoring, and might need support from a breathing machine.

Signs and symptoms of meconium aspiration syndrome may include:

• Dark green meconium in the amniotic fluid
• Abnormal heart rate patterns
• Pale or bluish skin color
• Poor muscle tone or limpness
• Lack of or poor respiratory effort at birth
• Abnormal breath sounds
• Breathing problems
• Meconium visualized in the mouth and throat
• Signs of infection – rapid breathing, raised body temperature, low blood pressure
• Chest X-ray showing the presence of meconium in the lungs.

The bottom line

Meconium is a normal first stool for your baby. It’s completely natural for it to be very dark in color. It is a normal function in a healthy newborn.

The first meconium poo is usually passed within the first 24 hours, with this stage lasting around 2-3 days following birth. As your baby begins to digest milk, the poo will change in consistency and color.

Sometimes a baby will pass meconium during labor. This is more common if you’re past your due date. If this happens, your care provider will want to monitor your baby’s heart rate closely for signs of fetal distress. Your baby will also be monitored postnatally for any breathing problems.

Rarely, this can lead to a condition called Meconium Aspiration Syndrome (MAS), where meconium is inhaled into the lungs. MAS can cause complications such as breathing difficulties and infection.

For further health information about Meconium Aspiration Syndrome (MAS), you can read.

Remember, not all babies who pass meconium in the womb will be distressed, and not all post dates babies will have meconium in labor.

If you’re concerned about your baby’s health or well-being, talk it over with your care provider.

Recommended Reading: 42 Weeks Pregnant | Your Body and Your Baby.