Baby's Fourth Month: A Guide to Development and Milestones

All about your 4-month-old baby!

Physical development: Baby is learning to roll over, says Seattle Children's Hospital's Dr. Michelle Terry. Help her learn to sit independently and position her to play on both her stomach and back.

Brain development: Your baby becomes more aware of her surroundings and wants to explore, says Princess Ivana. Her arms pump and legs kick as if she’s swimming in air. Wiggles get stronger. As hand-eye coordination gets better, your baby will be able to purposely grasp objects and find ways to taste the world — everything goes into her mouth. Be careful about what you leave within baby's reach.

Social development: Your baby can laugh, has babbling "conversations" with you and she recognizes the sounds in different languages, so it is not confusing for her to learn multiple languages at the same time, says Terry.

Fun fact or milestone: Peekaboo is a favorite game and she enjoys finding partially hidden objects. Watching herself in a mirror is sure to delight her, says Terry. She might become fascinated with other babies and older children.

What to watch for/common concerns: Terry says each child develops at her own pace, but talk to your child's doctor if your baby seems very stiff or floppy; can't hold her head steady; can't sit on her own; doesn't respond to noises or smiles; isn't affectionate with those closest to her; or doesn't reach for objects.

One important thing you can do for your baby: Work on establishing a routine for sleeping, feeding and playtime. Be flexible, but incorporate as much predictability for her as possible. Steps like a warm bath at nighttime and a certain music before feeding can become cues to help your baby learn what's coming next and how to calm down.