Meconium is your newborn’s first poop: a thick, sticky, blackish-green stool that Cleveland Clinic says your baby should pass within 24 to 48 hours after birth.
The first diaper you change may hold something that looks more like tar than poop. It is normal, it is temporary, and within a few days it gives way to the yellow stools most people picture.
This guide covers when meconium should appear, how stools change day by day, what diapers tell you about feeding, what stained amniotic fluid and meconium aspiration mean, and when a late first poop needs a call. Every clinical detail was checked in November 2026 against the sources named in the text.
Key Takeaways
Meconium is your baby’s first poop: blackish-green, thick, sticky and odorless (Cleveland Clinic).
Cleveland Clinic says the first poop should come within 24 to 48 hours after birth.
AAP HealthyChildren says breastfed stools turn greenish to yellow by days 3 to 4 and yellow with small curds by days 5 to 7.
Meconium-stained amniotic fluid is fairly common, but StatPearls says only 2% to 10% of those babies develop meconium aspiration syndrome.
Call if there is no meconium by 48 hours, the belly swells, or diapers fall short; green vomiting needs urgent care.
Table of Contents
What Is Meconium?
Quick Answer
Meconium is your newborn’s first poop. Cleveland Clinic describes it as blackish-green, thick and sticky, like tar, and says it has no smell. It is made of water, cells, urine, hair, mucus and other material your baby swallowed in the uterus. Cleveland Clinic says your baby should pass the first poop within 24 to 48 hours after birth.
Meconium builds up in your baby’s intestines during pregnancy. Cleveland Clinic explains that it forms as the fetus swallows amniotic fluid: the water is absorbed and the rest stays behind in the gut. StatPearls, the NIH-hosted medical reference, describes it as fetal cellular debris such as skin cells, hair and secretions.
Cleveland Clinic notes that care teams watch for meconium, and then for the change to regular newborn stools, as a check that the intestines are working.
What It Looks Like, and How It Differs From Later Poop
Feature
Meconium
Later newborn poop
Color
Blackish-green, very dark
Greenish to yellow by days 3 to 4, then yellow (breastfed babies, AAP)
Texture
Thick, sticky, tar-like (Cleveland Clinic)
Breastfed stool by days 5 to 7 is loose, with small curds (AAP)
Smell
None (Cleveland Clinic)
Has the smell you expect from poop
Meconium vs later stools, based on Cleveland Clinic and AAP HealthyChildren (read November 2026).
The stickiness surprises many parents, but it is normal. For every shade that comes after, see our baby poop color chart.
When Should Your Newborn Have the First Poop?
Cleveland Clinic says your baby should pass the first poop within 24 to 48 hours after birth, or within two days. Some babies pass it even before birth (more on that below).
If you had a home birth or went home early, note the time of each wet and dirty diaper so you can answer your provider’s questions.
If there is no meconium by 48 hours. Cleveland Clinic lists conditions that can delay or block the first stool: meconium ileus, cystic fibrosis, an intestinal blockage, an underdeveloped rectum, a meconium plug and Hirschsprung disease. A missing first stool is always something to tell your baby’s care team about, not something to wait out at home.
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From Black to Yellow: The Newborn Stool Transition Timeline
Once your baby drinks colostrum or formula, Cleveland Clinic says the rest of the meconium is pushed out and stools change to normal newborn poop. For breastfed babies, AAP HealthyChildren gives this picture:
Day of life
Number of stools (breastfed, per AAP)
What they usually look like
Days 1 to 2
1 or 2 a day
Blackish and tarry (meconium)
Days 3 to 4
At least 2 a day
Starting to look greenish to yellow (transitional stools)
Days 5 to 7
At least 3 to 4 a day
Yellow and loose, with small curds
Breastfed newborn stool pattern, from AAP HealthyChildren (read November 2026).
The in-between stools on about days 3 and 4 are often called transitional stools. AAP HealthyChildren adds that once your milk supply increases, many breastfed babies poop with each feeding during the first month.
Formula-fed babies pass meconium too, then settle into their own typical stools; our formula-fed baby poop guide covers that.
Poop and Wet Diapers as a Feeding Check
In the first week, diapers are one of the easiest ways to see whether a breastfed baby is getting enough milk. AAP HealthyChildren uses these benchmarks:
Stools: 1 or 2 a day on days 1 to 2, at least 2 on days 3 to 4, and at least 3 to 4 a day by days 5 to 7, with the color moving from black to yellow.
Wet diapers: by days 5 to 7, at least 6 a day, with urine that is nearly colorless or pale yellow.
Feeds: 8 to 12 nursing sessions every 24 hours.
Weight: AAP HealthyChildren notes that losing more than 8 to 10% of birth weight is a reason for closer follow-up.
AAP HealthyChildren also recommends a first checkup no more than 48 hours after you leave the hospital, a good time to bring your diaper notes. If stools are still black and tarry by day 4 or 5, or you see fewer stools or wet diapers than the benchmarks above, call your pediatrician.
Cleaning That Sticky First Poop Off Your Baby’s Skin
Meconium is sticky, so the first changes take longer. A few practical tips:
Have everything ready before you open the diaper: a clean diaper, wipes or soft cloths, and a small bowl of warm water.
Wipe gently from front to back with warm water on a soft cloth instead of scrubbing.
Pat the skin dry before putting on a fresh diaper.
Our step-by-step guide on how to change a diaper covers the basics for the newborn weeks.
Stained Amniotic Fluid: When Babies Poop Before Birth
Some babies pass meconium before they are born, into the amniotic fluid. When this happens, the fluid looks green or brown instead of clear (Cleveland Clinic). It is called meconium-stained amniotic fluid.
How common is it? Cleveland Clinic says it happens in 12% to 20% of deliveries, and MedlinePlus says more than 10% of normal pregnancies. StatPearls reports how often it rises with gestational age:
Timing of birth
Babies born through meconium-stained fluid
Preterm
5.1%
Term
16.5%
Postterm
27.1%
Rates of meconium-stained amniotic fluid by gestational age, as reported by StatPearls (read November 2026).
Why it happens. MedlinePlus says a baby may pass meconium before birth when stressed by reduced blood and oxygen supply, often from placenta or cord problems. StatPearls notes that passing meconium in the womb becomes more common after 37 weeks, and it is more frequent in pregnancies that go past the due date. It is one reason for closer monitoring at 41 weeks pregnant and beyond.
What it means for you. If your water breaks at home and the fluid looks green or brown, tell your provider or birth center when you call, because MedlinePlus says teams prepare for possible meconium at birth when the water breaks with stained fluid. Our water breaking guide covers what else to note. MedlinePlus says most babies born through stained fluid do not breathe it in and have no problems.
What the delivery team does now. ACOG’s Committee Opinion 689 says babies born through meconium-stained fluid should no longer routinely receive suctioning during delivery, whether they are vigorous or not. If your baby is vigorous, with good breathing and muscle tone, ACOG says routine intubation and suctioning of the windpipe are not required and your baby may stay with you for the first steps of newborn care. StatPearls adds that since 2015, resuscitation guidelines no longer recommend routine windpipe suctioning even for babies who are not vigorous. ACOG says a team skilled in full newborn resuscitation should be present, ready to help.
Meconium Aspiration Syndrome: What Parents Should Know
Meconium aspiration syndrome (MAS) is a breathing problem in a newborn who has breathed meconium-stained fluid into the lungs before, during or right after birth. MedlinePlus explains that meconium can block airways and inflame the lungs.
How often does it happen? Only a minority of babies born through stained fluid develop MAS: StatPearls says 2% to 10%, and MedlinePlus says about 5%. Cleveland Clinic adds that swallowing meconium is considered harmless; the concern is inhaling it.
Topic
What the sources say
Risk factors
A pregnancy well past the due date, reduced oxygen to the baby before birth, maternal diabetes or high blood pressure, a difficult delivery or long labor, and infection of the placenta (MedlinePlus).
Signs at birth
Bluish skin, labored or rapid breathing (grunting, using extra muscles to breathe), pauses in breathing or limpness (MedlinePlus). StatPearls also lists a slow heart rate and low oxygen levels.
Hospital treatment
Oxygen, a warmer, antibiotics for possible infection, and a ventilator or IV nutrition if needed. Severe cases may receive surfactant, nitric oxide or ECMO, a heart and lung bypass (MedlinePlus).
Recovery
Extra breathing and feeding support often ends within 2 to 4 days, though fast breathing may last several days (MedlinePlus).
Outlook
MedlinePlus calls the outlook excellent for most babies, with rare permanent lung damage. StatPearls says most affected babies recover fully.
Meconium aspiration syndrome at a glance (MedlinePlus and StatPearls, read November 2026).
MedlinePlus notes a rare but serious complication, persistent pulmonary hypertension of the newborn (PPHN), and says some babies with severe MAS cough or wheeze for years. If your baby is admitted to a special care nursery or NICU, ask what support your baby is getting, what the team is watching for and how you can help with care and feeding.
A Late First Poop: Hirschsprung Disease, Cystic Fibrosis and Plugs
A baby who has not passed meconium within the first two days is checked for a few conditions. Here is what your care team is thinking about:
Meconium plug and meconium ileus: both on Cleveland Clinic’s list of causes of delayed passage, along with cystic fibrosis.
Hirschsprung disease: Mayo Clinic describes it as a condition present at birth in which nerve cells are missing in the large intestine, causing a bowel blockage. Mayo Clinic says the most obvious sign is not having a bowel movement within 48 hours after birth, and other signs in newborns can include a swollen belly and vomiting that may be green or brown.
Intestinal blockage or an underdeveloped rectum: also on Cleveland Clinic’s list.
If your baby is already home and has not pooped, call. You do not need to figure out the cause; that is your pediatrician’s job.
Call 911 or go to the emergency room right away if your baby:
Has trouble breathing, turns blue or gray, or is limp or very hard to wake.
Vomits green or brown fluid. Mayo Clinic lists green or brown vomiting among the newborn signs of Hirschsprung disease, a cause of bowel blockage, so treat it as urgent.
Has jaundice along with a fever, is listless or is not feeding well. MedlinePlus calls this an emergency; see our baby jaundice guide.
Call your pediatrician the same day if:
Your baby has not passed meconium by 48 hours after birth (Cleveland Clinic) and you are home.
Your baby’s belly looks swollen or feels tight.
Stools are still black and tarry after about day 4, or there are fewer stools or wet diapers than the AAP benchmarks above.
Your baby has fewer than 6 wet diapers a day by days 5 to 7 (AAP HealthyChildren).
Jaundice is severe (bright yellow skin), keeps spreading, reaches the soles of the feet, or lasts more than 2 weeks (MedlinePlus).
Anything else about your baby’s diapers, feeding or color worries you.
MedlinePlus says every baby should be seen within the first 5 days of life to check for jaundice. Trust your instincts: a call about a diaper is never wasted in the newborn weeks. This article is general education, not medical advice.
Frequently Asked Questions
What is meconium made of?
Cleveland Clinic says meconium is made of water, cells, urine, hair, mucus and other material a baby swallows in the uterus. It forms as the fetus swallows amniotic fluid and the water is absorbed, leaving the rest in the intestines. StatPearls describes it as fetal cellular debris such as skin cells, hair and secretions.
How long do newborns poop meconium?
Usually for the first couple of days. AAP HealthyChildren says breastfed babies typically have 1 or 2 blackish, tarry stools a day on days 1 to 2, greenish to yellow stools on days 3 to 4, and yellow, loose stools with small curds by days 5 to 7. Stools that are still black after about day 4 are worth a call to your pediatrician.
What happens if a baby does not pass meconium within 48 hours?
Cleveland Clinic says a baby should pass meconium within 24 to 48 hours. A delay can be a sign of conditions such as a meconium plug, meconium ileus, cystic fibrosis, an intestinal blockage or Hirschsprung disease, so doctors examine the baby and may order tests. If your baby is home and has not pooped by 48 hours, call your pediatrician that day.
Is meconium aspiration syndrome serious?
It can be, but most babies recover well. MedlinePlus says about 5% of babies born through meconium-stained fluid develop it, and StatPearls gives a range of 2% to 10%. Treatment can include oxygen, breathing support and antibiotics in a special care nursery. MedlinePlus calls the outlook excellent for most babies, and support often ends within 2 to 4 days.
Does meconium in the amniotic fluid mean my baby is in distress?
Not always. MedlinePlus says babies may pass meconium before birth when stressed by reduced oxygen, but StatPearls notes it also becomes more common simply as pregnancy goes past 37 weeks and especially past the due date. MedlinePlus says most babies born through stained fluid do not breathe it in and have no problems. Your care team will monitor and be ready to help.
Does meconium smell?
No. Cleveland Clinic says meconium has no smell, unlike normal poop, and describes it as blackish-green, thick and sticky, like tar or sludge. Once your baby is feeding and the stools change, AAP HealthyChildren says breastfed stools turn greenish to yellow by days 3 to 4 and yellow by days 5 to 7, and they will smell more like ordinary poop.
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