I have a 3 months old who still has a startle reflex. when should that go away and how can i tell if it is a seizure instead?

Startle reflex: Is your three monther premature? Normally the startle reflex goes away after 4 months or so for a full term baby. It takes longer if your baby was premature. This is probably not a seizure. If this was a seizure, it would occur spontaneously. A startle reflex can be provoked. That is a significant difference. Sounds like your baby is alright!

Relax: A startle reflex in sleep until 4 mo and awake into the mid 3 mo level is normal for a term born infant. If early, the expectation is adjusted week for week before due date.Discuss with your doc if you are concerned.