What is Reflux In Babies?

It seems that every baby at some time has experienced reflux. And while most of us have an idea of what reflux is, the specifics can still be a little confusing. Like most baby related conditions it can help to understand the reasons for our baby’s behaviour so we can care for them in the best possible way.

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Reflux is the shortened term for Gastro-oesophageal reflux, or GOR.  Because babies are small and their digestive system is immature, milk can easily pass from their stomach back up into their oesophagus (food pipe).  The oesophagus is the tube which connects the mouth to the stomach.

Another cause for reflux is when the sphincter, or muscle at the bottom of the oesophagus relaxes and allows milk to flow back out of the stomach. Ideally, the sphincter opens to let milk into the stomach and then closes to keep milk in. When the sphincter relaxes for too long, or it’s immature, acidic milk flows back into the oesophagus. This can cause heartburn, vomiting and nausea. Sometimes the milk goes into the trachea (windpipe) which causes coughing or infection.

With time and gut maturity, most babies outgrow reflux and have no long lasting digestive problems because of it.

What Causes Reflux?

A baby’s gut is immature. Just like the rest of their body, growth over time increases the size of their stomach and the way their body functions. The muscles involved in keeping milk down and within the stomach can be lax and the sphincter at the top of the baby’s stomach more open than it could be. This combination of muscle relaxation and an open inlet means that milk easily refluxes back up into baby’s oesophagus. The shortness of a baby’s oesophagus and distance between their mouth and their stomach means that reflux is common.

First, the Basics

Milk begins its digestion in the mouth and then, when it reaches the stomach, enzymes and acid are released to help break it down. The lining of the stomach is designed to withstand the effects of acid; however, the oesophagus is not.  As the milk rises up into the oesophagus it can cause pain. 

Some babies seem to bring up milk as effortlessly as they smile. Without any warning, milk comes out of their mouth as easily as it flowed in. On a spectrum of reflux-related symptoms, these babies are the easiest to manage.  The most difficult aspect to their care is making sure there’s always an absorbent towel or cloth close by during, between and after they’ve fed.

Other babies show some distress when they reflux. There can be discomfort or pain as the milk regurgitates from their stomach into their oesophagus. This may also be influenced by uncomfortable gut sensations which cause the baby to feel insecure.  This is one reason why soothing and reassurance from parents can make a big difference to babies who are experiencing reflux symptoms.

What’s important is that as long as the baby is still mostly happy and continues to gain weight, there is no value in treating their reflux or doing anything special.

When Do I Need to Be Concerned About My Baby’s Reflux?

It’s estimated that around 70-85% of babies experience regurgitation within their first two months of life. This resolves, without intervention, in around 95% of babies by the time of their first birthday.

It is true that over this time span, some babies do need more active treatment for their reflux, especially when it is impacting on their growth and general health.  Changes in position, holding them upright after feeds, gentle handling and comforting can all make a big difference.

Sometimes changes in feeding are recommended, especially if the baby is also showing signs of sensitivity to specific milk proteins. Where necessary, medications may also be prescribed to help reduce the symptoms of discomfort and improve the way milk is digested within the stomach.

How Would I Know If My Baby Has Reflux?

Reflux is blamed for a lot of unsettled baby behaviour. In fact, reflux and colic are often attributed as  being  the main reasons for crying in otherwise healthy, thriving young babies.

Given that reflux is so common - most newborns experience reflux - why does it happen?  The answer lies in gut immaturity. The sphincter at the end of the oesophagus (food pipe) should be tight to keep milk within the stomach. But in newborns this valve can be loose.

Eventually the tone of the sphincter improves so it works more efficiently; but in the meantime, acidic stomach contents easily ‘spill’ out of the stomach and back up the oesophagus. Sometimes this leads to vomiting or reswallowing the milk and food before it comes out of the baby’s mouth.  

Premature babies are more likely to experience reflux than babies who are born at term.

What Are the Signs of Reflux In a Newborn?

  • Frequent vomiting or positing. If you always need to make sure your baby is wearing a bib, their clothing frequently moist and you need to keep a cloth close by, your suspicions about reflux are probably spot on.
  • Seeing your baby reswallowing, back arching and looking like they are in pain. Though be mindful these are also symptoms of GORD. It’s said that babies experience similar feelings of indigestion and heartburn as adults when they’re refluxing. If your baby is behaving in a familiar way this can be a clue.
  • It’s fair to suspect reflux if your other children had reflux, and the new baby is showing the same signs and symptoms. You know your baby better than anyone else. Trust your own instincts and always follow your gut feeling about having them checked out.
  • Slow growth or weight loss because of vomiting. Gastro Oesophageal Reflux Disease is the condition where reflux is more severe and starting to compromise the baby’s growth. 
  • Fussy feeding or even refusal to feed. Your baby may start sucking and then after a few minutes start pulling away, closing their mouth and crying. Some babies become agitated when they see the breast or bottle before feeding as they anticipate pain.
  • Bringing up small amount of milk when they burp. Positing is the formal name for these small spills. They’re not a large enough volume to describe as a vomit, more a 5-10ml spit up.
  • Changes in sleep and settling behaviour. Babies who reflux may settle to sleep easily but wake before they usually do. NB there are many causes for changes in sleeping patterns.  In isolation of other symptoms, sleep changes are not a definitive diagnosis of reflux.
  • Smelly, acidic smelling vomit. Babies with reflux often have a particularly ‘sickly’ smell.  They smell like sour milk and their clothing always needs changing.

Reflux (GOR) and Gastro-Oesophageal Reflux Disease (GORD)

There is a Difference

  • Gastro-Oesophageal Reflux (GOR), commonly known just as ‘reflux’ is the effortless regurgitation of stomach contents into the oesophagus (food pipe). The baby may or may not spill small amounts of milk out of their mouth.
  • Gastro-Oesophageal Reflux Disease (GORD) happens when reflux is impacting on the baby’s growth and weight gain. Complications of GORD can include respiratory signs, changes in feeding and the baby’s general well-being. Babies with GORD may need medication to help manage their symptoms.

GORD can cause:

  • Changes in sleep and settling behaviour
  • Weight loss
  • Vomiting and blood to appear in the baby’s vomit
  • A chronic cough or wheeze
  • A lack of enjoyment for parents caring for their baby. When GORD symptoms result in long hours of crying, frequent vomiting and little respite, GORD can take a toll on the most patient and loving of parents.

Babies with reflux may vomit or possit without any warning. One minute they seem fine and the next their chest and whoever’s holding them is covered in vomit.  It’s easy to pick the parents of a baby with reflux as they often have white spills down their back.

Some babies with reflux bring up their milk with force and others seem to have more of a dripping tap style. Whichever category your baby fits into, know that you are not alone.

It’s estimated that around 70-85% of newborn babies will experience some regurgitation of their stomach contents within their first two months of life. And although this statistic is intended to be reassuring, it’s unlikely to make much difference to you, especially if all you feel you’re doing is holding and rocking your baby.

How Can I Be Sure?

At what point is it fair to say with 100% certainty that a baby is refluxing?  The truth is, reflux can be a difficult condition to diagnose. Even health practitioners can find it difficult to accurately diagnose reflux in a baby. Sometimes reflux is given as a ‘default’ reason for a baby’s crying. 

The days of every baby having a prescription for reflux have passed.  Now we have a better understanding of the normal physiology of a baby’s gut and know that in time, the majority of babies outgrow reflux. Importantly, most do not have any longstanding gut or health issues because of it.

Sometimes babies with reflux bring up milk when they burp, others at the end of a feed, while others wait until a couple of hours after they’ve fed to deposit a portion of their last feed.


Always speak and check with a qualified nurse or healthcare professional about your baby to understand what your baby’s individual needs are, especially if you are ever concerned about your baby's well being.

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