Your baby's startle reflexes will begin to disappear as they grow. By the time your baby is 3 to 6 months old, they probably won't demonstrate the Moro reflex any longer. They'll have more control over their movements, and their reflexes will become less jerky.

Why does my baby keep flinching?

But researchers believe that twitching may actually be part of a baby's motor skills development. When a baby's body twitches during rapid eye movement (REM) sleep, it's triggering circuits throughout the brain to teach newborns about their limbs and how to use them, University of Iowa researchers believe.

When do babies stop startling?

While every baby is different, most parents notice their baby's startle reflex begin to go away at around 3 months and disappear between 4 and 6 months. In the meantime, don't sweat the startles (they're all signs of healthy neurological development).