By 4 months, many babies smile on their own to get attention and use movement or sound to interact with a caregiver.

Social/Emotional

  • Often smiles on their own to get your attention.
  • Chuckles when you try to make them laugh.
  • Uses movement or sound to keep you engaged.

Language/Communication

  • Starts making vowel sounds like “oooo” and “aahh.”
  • Responds vocally when spoken to.
  • Turns toward the sound of a voice.

Cognitive (Learning, Thinking, Problem-Solving)

  • May open their mouth when they see a breast or bottle.
  • Shows focused interest in their own hands.

Movement/Physical Development

  • Holds their head steady without support when held.
  • Holds a toy placed in their hand.
  • Swings at a dangling toy.
  • Brings hands to mouth often.
  • Pushes up onto elbows during tummy time.

Caregiving Tip

Bringing hands to the mouth is a common, natural way babies explore at this age. Easy-to-grip toys like a rattle, plus tummy-time play, can help support arm muscle development.

When to Consider Talking with a Pediatrician

If several of these are missing — especially holding their head up or reacting to sound — it’s worth mentioning to a pediatric provider. This information isn’t a diagnostic tool and doesn’t replace advice from a medical professional.