Key takeaways: Meconium is thick, dark, sticky stool made from what your baby swallowed in the womb. Most healthy term babies pass it within the first 24 to 48 hours. Stools should turn green and then yellow by about day 4 or 5. No stool by 48 hours needs evaluation.
Your baby’s first diapers may surprise you. Meconium is black or very dark green, thick, and sticky like tar. It’s completely normal.
What Is Meconium?
Meconium forms in the intestines during pregnancy. It’s made of amniotic fluid, mucus, bile, skin cells, and lanugo (fine body hair) that your baby swallowed in the womb. It has little odor.
When Should It Pass?
Most healthy term babies pass their first meconium within the first 24 hours, and nearly all within 48 hours. Premature babies may take longer.
How Stools Change
- Days 1 to 2: black, sticky meconium.
- Days 3 to 4: transitional stools, greenish-brown and looser.
- Days 4 to 5: yellow, seedy stools for breastfed babies; tan or yellow-brown, pastier stools for formula-fed babies.
This change is a sign that your baby is getting enough milk. Colostrum acts as a mild laxative, helping meconium pass.
From the author
From First Breath to First Birthday is my month-by-month guide to your baby’s first year, written as a NICU and postpartum nurse. My book starts in the first hours after birth and walks you through every newborn check and the weeks that follow.
Cleaning Tips
Meconium is sticky. A thin layer of petroleum jelly on your baby’s bottom after each change makes the next one much easier to clean. Use warm water and soft cloths or gentle wipes.
Meconium Before Birth
Sometimes babies pass meconium before birth, staining the amniotic fluid green or brown. This is more common in babies born after their due date. Most babies are fine, but rarely a baby can breathe meconium-stained fluid into the lungs (meconium aspiration syndrome), causing breathing problems. Your care team will watch your baby closely if there was meconium in the fluid.
When a Delay Needs Attention
If your baby hasn’t passed meconium within 48 hours, your care team will evaluate them. Delayed meconium can be a sign of conditions such as:
- Hirschsprung disease (missing nerve cells in part of the colon).
- Meconium ileus, which is often associated with cystic fibrosis.
- Meconium plug.
- Other bowel blockages.
Tell your nurse or call your baby’s doctor if your baby: hasn’t passed stool within 48 hours, has a swollen belly, is vomiting (especially green vomit), or isn’t feeding well. Green vomit is an emergency.
The Bottom Line
Black, sticky meconium is your baby’s normal first stool. It should pass within 24 to 48 hours and give way to yellow stools by day 4 or 5. A delay needs a medical check.
Want more support for your baby’s first year? My book, From First Breath to First Birthday, is available on Amazon.
Related Articles
- The Newborn Diaper Guide: Poop Colors, Pee Counts, and When to Worry
- Your Newborn’s First 24 Hours: What Happens in the Hospital, Hour by Hour
- Constipation in Babies: What’s Normal Straining and What Isn’t
Sources
- Altmann TR, Hill DL, eds. Caring for Your Baby and Young Child: Birth to Age 5. 7th ed. American Academy of Pediatrics; 2019.
- Meek JY, Noble L; Section on Breastfeeding. Policy statement: breastfeeding and the use of human milk. Pediatrics. 2022;150(1):e2022057988.
- Kenny SE, Tam PK, Garcia-Barcelo M. Hirschsprung’s disease. Semin Pediatr Surg. 2010;19(3):194-200.
- Wiswell TE. Handling the meconium-stained infant. Semin Neonatol. 2001;6(3):225-231.
This article is for general education and is not a substitute for individualized medical advice. Always talk with your baby’s health care provider or your own provider about your specific situation. If you think your baby or you may have a medical emergency, call 911.
