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.