Meconium: what your newborn's first poo looks like and how long it lasts

Meconium is your newborn's first poo: thick, sticky and black or greenish-black. HealthHub says babies pass it for the first 2 to 3 days after birth. It is made during pregnancy, before your baby has had any milk. Once feeding gets going, the stools turn lighter, and by the end of the first week they are usually yellow.

When the first poo comes

Meconium builds up in your baby's gut while you are still pregnant. An NHS maternity unit describes it as produced during the pregnancy, usually green-black and very sticky. That is why the first nappies look so different from the ones that come later.

The NHS says some babies pass it during or just after birth, and others some time in the first 48 hours. Mayo Clinic gives the same window: the first dirty nappy usually comes within 24 to 48 hours of birth.

From black to yellow in the first week

Expect the colour to change quickly. KKH says babies have blackish stools for the first two to three days, which turn golden yellow or yellowish brown over the first week. NUH describes the same shift from black to brown to yellow.

After that, HealthHub says breastfed babies usually pass bright mustard-yellow, loose stools with small seed-like bits, while formula-fed babies have pastier yellow or tan stools. How often varies a lot. KKH says anything from 8 to 10 stools a day to one every three or four days can be normal, and a red face and straining sounds while pooing are normal too.

The ward nurses will ask about nappies, so it helps to jot them down. Our newborn feed and nappy log does that on your phone, and the baby poop guide shows what each colour means.

If your baby has not passed meconium

If your baby has not passed any stool within the first day or two, tell the nurse or doctor. The NHS lists failing to pass meconium within 48 hours as one sign of Hirschsprung's disease, a bowel condition babies are born with. Other signs are a swollen belly and vomiting green or yellow-green fluid. It also notes that some babies with the condition do pass meconium, so a swollen tummy or green vomit needs a doctor either way.

Later on, a few stool colours need a call to the doctor. KKH says to seek medical attention for pale or clay-coloured stools, fresh blood in the nappy, frequent large watery stools, or hard dry stools that are difficult to pass. Pale stools can also go with neonatal jaundice that needs checking.

Meconium-stained waters at birth

Sometimes a baby passes meconium before birth, and it colours the amniotic fluid. You may hear the team call this meconium-stained liquor. NHS maternity advice from Wales says green or brown waters can be a sign your baby has had a poo inside you, and that your baby then needs monitoring to make sure they are not in distress.

So if your waters break and look green or brown, the same advice says to call your maternity unit immediately. See water breaking for the rest of what to look out for, and Apgar score for the checks your baby gets in the first minutes after birth.

Frequently asked questions

What is meconium?

It is your baby's first poo, made in the gut before birth. HealthHub describes it as sticky, thick and dark green, and says it should not last more than a few days.

How long does meconium last?

About 2 to 3 days, HealthHub and KKH say. By the end of the first week the stools are usually yellow.

What does meconium-stained mean?

It means meconium was found in the amniotic fluid because your baby passed some before birth. NHS maternity advice says green or brown waters mean your baby needs monitoring to check they are not in distress, so call the labour ward if you see it.

My baby's poo is still black after a week. Is that normal?

Meconium itself should be gone within a few days. KKH notes that iron supplements can turn stools brown or black. If your baby is not on iron and the stools are still black, ask your polyclinic or doctor.

Related terms

• Neonatal Jaundice: Yellowing of a newborn's skin and eyes from bilirubin. Common and usually mild, but checked in every baby.
• Neonate (Newborn): The medical word for a newborn baby in the first 28 days of life.
• Colostrum: The thick yellow first milk your body makes in the first few days after birth.
• Apgar Score: A score out of 10 given to your newborn at 1 and 5 minutes after birth to check if they need help.
• Rupture of Membranes (Water Breaking): When the bag of fluid around your baby breaks and leaks out through the vagina, as a gush or a trickle.

See every term in the glossary