Why does my baby keep sticking her tongue out?

One of the first ways a baby socially communicates with a parent is to imitate facial movements, such as sticking out a tongue, according to "Parents" magazine. In some cases, parents do this subconsciously, but doing it intentionally is a good way to interact and test a baby's social intimacy.

After a few weeks, some babies learn that if they stick out their tongue, a parent will mimic the behavior, according to Johns Hopkins Medicine. Babies also use their tongue for functional communication. Breastfeeding babies use their tongues to push away the breast as an indication of being full, according to The Island Packet.