3 month old spits up after every bottle! gaining weight and doesn't cry after spit up! generally, a happy baby! reflex? switch formula? allergy?

GER vs Gerd: many babies spit up and have gastro-esophageal reflux there is a version where the kids get fussy and are suffering pain from acid reflux if a baby is just a spitter and not fussy, i try to reassure parents that this is a process that should resolve spontaneously by 6 monts If this is still an issue or the vomiting is super bothersome there are formulas like enfamil AR that is for spitters

Spit ups: spit ups are very common and if your baby is gaining weight and the spit ups are not assoc with crying or pain, there does not need to be any interventions. Common reasons for spit ups can be reflux, but also related to over-feeding. How many ounces are you giving per feed? Techniques to reduce spit ups: freq burping, holding upright, & others. This is a great reason to call ped for phone consult

Happy spitter: In my experience the happy spitters are refluxers.This process tends to increase to peak at about 4 mo and gradually decrease after 6-8. Thickening feed can help and antacids help if they are fussy.

Thicken Feeds: You can try thickening the feeding with one teasoon of rice cereal per ounce of formula, feed the baby just a smaller feeding and more often, elevate the head of the bed, and keep him upright between feedings as much as possible. If he is gaining weight, happy and not having painful feedings, I'd try these simple measures. Be sure and make your four month appt with his pediatrician!