Why Do Newborns Have Green Stool?

Why Do Newborns Have Green Stool

What Causes Newborns Green Stool?

It is not uncommon for newborn babies to have a green stool after they have been fed. Once a mother finishes breastfeeding her baby, sometimes the baby puts out a green stool. This phenomenon is quite common, and many newborns experience this reaction. If any mother sees that her baby is putting out a green stool, she does not have to worry about anything. It does not indicate any sickness or any harm to the baby’s health. Newborns are different than adults in age and body size as well as in terms of body composition.

There are many reasons why a baby’s stool might turn green. One example is that the baby might be facing indigestion, or the baby’s body might not be comfortable in its surrounding environment. To understand more about why this happens, read further:

What is the Normal Colour of a Baby’s Stool?

The green colouring substance that turns some babies’ stool green is naturally created in their small intestine. Only in some cases, the colour is excreted along with the stool, which we then see as a complete green stool. Green is not the set colour of a baby’s stool. The consensus is that the colour of a baby’s stool is more or less supposed to be a mustard colour, at least for the first few months of its life.

This mustard colour of the stool occurs only if the baby’s mother is actively breastfeeding it. Otherwise, it might be of a different colour altogether. Parents should avoid comparing different stool colours as it would only serve to worry them. They need to understand that not all babies are the same. As a baby grows older, he or she starts to develop even more shades of colours until they become a full-grown child. At this point, his or her stool will only change under certain circumstances.

What are the Types of Colours of a Newborn’s Stool?

A baby’s stool might change colours throughout its infancy. Here is a timeline during which a baby might undergo multiple different stool colours.

  • Sticky black or dark green for the first excrement that the baby poops out.
  • Yellowish green for the next 3-4 days.
  • When the baby is breastfed, eventually, the stool color starts to turn into a mustard color within a couple of days.
  • Red stripes might indicate an allergic reaction to breast milk.
  • Sticky green or light yellow indicates a viral infection.

There are many other colours and shades that the baby’s stool might change to, but it is not a significant health risk. Nevertheless, parents have their right to take precautionary steps and talk to their paediatrician if they feel the need to do so.

How Does the Baby Stool Turn Green?

Numerous factors contribute to a green stool from a baby, and pretty much none of these factors pose a significant health risk to newborn infants. Regardless, parents, especially mothers, should keep a close eye on their babies during this time to make sure that nothing is amiss.

How Does a Change in Environment Affect Baby Stool Colour?

You may not know this, but many babies interact with the outside environment quite differently as compared to living in a hospital where they are kept for only a few days. This is because it takes time for the baby to truly adapt to its surroundings, and it takes even longer for the body to make decisions regarding how it’s meant to function and how the baby must operate.

In terms of the environment, the temperature and pressure at which the baby is kept correspond with the stool colour of the baby. If it is too cold, for example, then the intestine walls contract too quickly. This way, they do not give the baby enough time to be restored to its normal state.  Therefore, the excreted stool has a greenish colour to it.

This is a common occurrence in many parts of the world, where the temperature is often very low. The baby’s stool in the early days is always green because of the cold temperature. So parents should not worry if their infant is born during the winter and his or her stool is green. Parents can counteract by addressing the cold as best as they possibly can. They can make sure that the belly of the newborn is always warm and that the baby’s room is warm and comfortable.

Does Food Affect the Baby’s Stool Colour?

There are two ways in which food can affect the stool colour put out by the newborn baby. They are:

Not enough food or milk is consumed: for a newborn, consuming as much protein, fats, and carbohydrates, as recommended by its paediatrician, is necessary. If a baby does not eat regularly, then he or she might end with an empty stomach by the end of the day. Due to this, the baby’s intestine might not have enough material moving through it, and as a result, the walls contract more frequently. This contraction of the intestine walls releases the substance that eventually changes the colour of the excreted stool to green. 

This factor is usually not that common because most mothers make sure that their children are well-fed and do not have to go a whole day without consuming anything. 

Quality of the food consumed is not the best: Sometimes, the food you are giving your baby is not up to the standard. This does not mean that the digestive system has any problems in digesting it completely. Rather, this means that the food consumed might result in an unwarranted chemical reaction. Since we know that many substances inside the stomach can cause this reaction, there is a high probability that the green colour of the stool is because of this factor.

Food is not well digested: In some cases, the baby is not able to digest the food it consumes. The food a baby normally consumes is soft and is often a different colour. Say you give your baby a milk formula instead of breastfeeding it and your baby consumes a green iron formula. There is a possibility that the baby does not digest the entire food and some of the green pigment from the food turns the colour of the stool green.

How Does Breastfeeding Change the Stool Colour of a Newborn Baby?

Baby stool turns green due to the effect of several chemical reactions that take place in a breastfeeding baby. Mothers who regularly breastfeed do not need to worry if their child starts to put out green stool. This is because the green colour is not because of breastfeeding. Rather, it is due to the chemical reactions taking place inside the baby’s digestive system.

When a mother breastfeeds her newborn, a sequence of chemical reactions occurs within the intestine track that links to the baby’s stomach. There is a substance known as bilirubin which plays a major role in turning a newborn’s stool green. It is found in the upper parts of the small intestine that links with the large intestine. The intestine track contains biliary erythrin and bilirubin that take part in the chemical reaction, which eventually turns the newborn’s stool yellow-green.

As soon as the stool is pushed against the colon of the newborn, the biliverdin is reduced to a simple compound, which is then turned into bilirubin. As soon as the stool exits the colon, it turns yellow. This is what happens when a baby’s stool comes out yellow.

A breastfeeding baby consumes acidic milk from his or her mother. A mother’s milk is always acidic, so this is normal. This milk interacts with the bacteria that are normally found in the stomach. As a result, the excreted stool has a greenish tint that appears alarming to the mother, but it is quite normal for a breastfeeding baby.

Is a Different Coloured Stool From Breastfeeding Alarming?

Parents might think that a different colour stool might signify some serious illness in a newborn baby, but that is not the case. Parents should rest assured that their baby is quite safe and that this is a normal phenomenon that is quite common in the world. The colour change of the stool will eventually wear off as the baby grows and adapts better to the environment around him or her.


In the end, parents should be aware of the different colours and shades of a stool that might indicate an infection or allergic reaction. However, they should not worry all the time since this might cause them to lose focus on what’s important, and that is interacting with the baby. Parents should take every part of the baby’s day and wellbeing very seriously, but they should not rush to judgments on their own. It is best to stay calm and consult a paediatrician whenever they have a question, either about green stool or anything else regarding their children, before jumping to any conclusions and unnecessarily worrying themselves.

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