Meconium Stools and Transitioning to Normal Baby Stools

Normal Meconium, Failure to Pass Meconium, and Meconium Staining

baby having his nappy changed
How long do meconium stools last and what else do you need to know?. Getty Images/Rayes

How long do babies have those black tarry and sticky stools called meconium? This is a common question, especially because meconium stools are rather hard to clean up.

What exactly are meconium stools? What does it mean if your baby doesn't have meconium stools? And what happens if your baby passes meconium before she is born?

What are Meconium Stools?

Meconium stools are the large dark, black or greenish-black, thick, tarry, sticky bowel movements that newborn babies have during their first two or three days after birth.

Meconium is made up of cells and substances that line the digestive tract during pregnancy.

It is the combination of these adjectives, especially 'large,' 'thick,' and 'sticky,' that make meconium stools hard to clean up and don't make many new parents look forward to these dirty diapers.

Fortunately, meconium stools do not smell bad. While this was once thought to be due to meconium being sterile, studies have found bacteria in the meconium of healthy babies.

Transitioning to Normal Baby Stools

Meconium stools are quickly followed by transitional stools by the time your baby is three to five days old. These stools are a little looser, more greenish-brown in color, and are the "transition" to regular milk stools on about day six.

If your baby is still having meconium stools after he is three days old or transitional stools after he is five days old, It's important to talk to your pediatrician.

A delay in the transition of meconium or transitional stools to milk stools may be a sign that your baby is not eating enough or other concerns. (Learn more about the signs to watch for to know if your baby is getting enough breastmilk.)

What is "normal" and what is not? In general, you can usually expect that your baby will have:

  • 3 meconium bowel movements on day two that are likely still thick, tarry, and black
  • 3 bowel movements on day three, with the stools becoming looser and greenish to yellow in color (transitional stools)
  • 3 yellow, soft and watery bowel movements on day four
  • 3 yellow, loose and seedy bowel movements on day five
  • 3 larger, yellow, loose and seedy bowel movements on day seven (milk or breastfeeding stools)

Again, be sure to talk to your pediatrician if your baby isn't following this pattern, but, just as adults vary in many ways, babies can vary in the time it takes to progress from meconium stools to milk stools.

Failure to Pass Meconium

Although many parents are worried that their babies will just never stop filling their diapers with meconium, some babies have the other problem and simply don't have a meconium stool on their first day or two of life.

The majority of healthy full-term babies pass their first stool within 48 hours of being born, and most will have a meconium stool within 24 hours of birth. If your baby does not have a bowel movement or pass a meconium stool, it could be a sign that something is wrong.

Conditions which may result in a failure to pass meconium include an intestinal obstruction, meconium ileus (which can be associated with cystic fibrosis,) Hirschsprung's disease, meconium plug syndrome, or an anorectal malformation, which can include anal stenosis (an abnormally small opening at the anus, or an absent anus (anal atresia.)

If babies are unable to pass meconium they may develop a distended abdomen, vomit, and do not generally feed well. In addition to a physical exam and simple x-rays, other radiologic studies and tests may need to be done to figure out exactly what is causing a newborn baby to have have a delay in passing meconium.

Meconium Staining

Much more common than having a problem in which a baby fails to pass any meconium, a baby may pass meconium before birth, leading to meconium stained amniotic fluid and a meconium stained baby.

Meconium staining on its own isn't dangerous, though it can be frightening to see your baby covered in meconium at birth.

Meconium staining can become a problem, however, if a baby aspirates (breathes in) this meconium into her lungs. Meconium aspiration pneumonia is a serious condition often requiring careful monitoring in the neonatal intensive care unit.

Why do baby's pass meconium before they are born? Although meconium staining can sometimes happen normally, especially in babies who are overdue, it may also occur in a baby who is undergoing some kind of stress. Stressors may include both conditions involving the baby, such as an infection, or if the baby's mother has high blood pressure, gestational diabetes, preeclampsia, oligohydramnios (low amniotic fluid,) or if she smokes cigarettes heavily.

Guidelines put forth by the American Academy of Pediatrics and the American Heart Association in 2005 and 2015 have further defined the best management for babies with meconium stained amniotic fluid. In the past, vigorous suctioning of the mouth and nose was done for babies with meconium staining after delivery of the head and before delivery of the shoulders. In babies that are vigorous with good muscle tone and respiratory effort, this suctioning does not appear to make a difference and is no longer recommended. In contrast, for babies with poor respiratory effort or poor muscle tone, intubation (placing an endotracheal tube) and applying suction below the glottis is recommended at birth, followed by close follow-up. It's now recommended that medical professionals who can provide intubation and suctioning be present when meconium stained amniotic fluid is noted prior to birth.

When meconium is very thick and detected before or early on during labor, a procedure known as amnioinfusion is sometimes recommended. In this procedure, sterile saline solution is injected into the uterus in order to dilute the meconium.

Bottom Line on Meconium Stools and the Transition to Normal Stools

The majority of babies will have meconium stools within the first day of life, which slowly become less tarry and thick over the first week of life. While these stools are often messy and difficult to clean, applying a small amount of ointment to your baby's bottom will make diaper changing much easier.

The failure to pass meconium in the first 24 hours may be a sign of a medical condition such as an intestinal obstruction and your pediatrician should be contacted. More commonly, babies pass their first meconium stool prior to birth resulting in meconium staining. On its own this is not serious, especially if a baby only passes "light" meconium. If the meconium is thick and a baby is distressed at birth, however, suction (and possibly amnioinfusion) is recommended to reduce the chance that the baby will breathe in the meconium and develop meconium aspiration syndrome.

For other concerns you may have, check out this guide to your baby's first week of life.


Committee on Obstetric Practice. Committee Opinion No 689: Delivery of a Newborn With Meconium-Stained Amniotic Fluid. Obstetrics and Gynecology. 2017. 129(3):e33-e34.



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