Why does my baby take two sips out of a bottle and spit it out?

What the evidence says

This is a really common thing parents notice, and in most cases it isn't dangerous. Babies naturally stop when they feel full, so if your baby pulls off after a couple of sips, that may simply mean they've had enough for now, especially if they're otherwise happy, gaining weight, and having plenty of wet diapers. Other common causes include a nipple flow that's too fast (causing choking or gulping) or too slow (causing frustration), silent reflux where milk comes back up but is swallowed rather than spat out, teething discomfort, an ear infection, or a cold that makes sucking and swallowing uncomfortable.

Some babies also go through a temporary phase called bottle feeding aversion, where they become fussy or resistant around bottles for a stretch of time. Things that can help: check the nipple size and flow, keep feeds calm and low-pressure, follow your baby's hunger cues rather than pushing them to finish, and burp partway through feeds. Avoid switching bottles or tricks to force acceptance, since this can sometimes make aversion worse.

See your doctor if the pattern lasts more than a couple of weeks, if your baby seems to be losing weight or not gaining well, if they arch, gag, or seem to be in pain during feeds, or if you're worried about dehydration.