Newborns do stop eating when full as they do have the innate ability to regulate their fullness and hunger cues.
When your newborn is full they will often turn away from the bottle or breast and may even fall asleep during feeding or may spit up or vomit or become irritable or fussy or even push the breast or bottle away.
Spit up can also mean overfeeding in some cases, although spit up also occurs due to swallowing of air and also because of immature esophageal muscles.
Spitting up in babies is very normal even when they are not overfed as the babies digestive systems is still developing.
The muscle that is at the top of the babies stomach or lower esophageal sphincter is not fully developed, which allows the baby's stomach contents to easily come back up.
Babies also tend to swallow air when they are feeding, which can also put pressure on the baby's stomach and cause spitting up.
A baby's stomach is also small and overfilling it by overfeeding can also lead to reflux.
In other cases spitting up can also be related to forceful milk ejection reflex, especially in breastfed babies or even a tight pylorus which is the valve at the bottom of the stomach.
After feeding your baby you should sit your baby up for 15 to 20 minutes long to help prevent gas and spitting up.
After you feed your baby they should sit up for 15 to 20 minutes and should also be burped to get rid of some of the air and also burp your baby frequently during feeding and after feeding.
Hold your baby upright and lean them slightly forward and if your baby has reflux you may need to sit them upright for a bit longer.
If yoru baby seems content and has not spit up, you might gradually reduce the upright time.
The age that reflux peaks in babies in between the ages of 4 months to 6 months of age.
Reflux and spitting up is common in babies and a normal thing as the muscle that prevents the stomach contents from flowing back up into the esophagus also known as the lower esophageal sphincter or LES is not yet fully developed in young babies.
As the baby grows and their lower esophageal sphincter strengthens, the reflux usually gets better and often resolves by the time the baby is 12 months to 18 months old.
A happy spitter is a baby that spits up frequently but is otherwise healthy and also content.
Happy spitter babies often gain weight very well and are not bothered by the spitting and they don't show any signs of discomfort or pain.
Spitting up is a normal part of the infants development and is also often called GER or physiologic gastroesophageal reflex.
A baby spitting up is very normal and does not mean anything is wrong with your baby unless they cannot keep any formula down at all.
Most babies will naturally spit up in the first few months of their life.
And the spit up is often a result of the muscle that is at the top of the baby's stomach also known as the lower esophageal sphincter not being mature fully and closing tightly, which allows for the stomach contents to come back up.
The signs that your baby is a happy spitter are the baby is eating well and gaining the appropriate weight and they are thriving even though they are spitting up.
Babies that are also happy spitters are not bothered by the spitting and don't seem distressed or don't seem to be in pain during or after the spitting up.
And some babies that are happy spitters are also happier and feel better after spitting up.
Happy spitters also tend to spit up frequently even with every feeding.
Spitting up can be a concern if the baby is frequently vomiting which is projectile vomiting or forceful vomiting or they are not gaining weight, can't keep any formula down or are showing signs of pain.
It could in those cases be a sign of GERD or another issue and if so you should see the baby's pediatrician to be safe.