Month 1

Physical

Weight may decrease during first week of life. Lies flexed, like in the womb; barely lifts head while on stomach; leg and arm movement consist of uncontrolled writhing and purposeless hand opening and closing; bears no weight on legs; holds hands tightly fisted; can't hold a rattle.

Language/social

Makes demanding cries, grunting throaty sounds, fleeting smiles, sleep grins; discriminates parents' voices; sees best at 8-10 inches; has blurred vision; has erratic sleep and feeding schedule. Smiles involuntarily.

Cognitive

Displays instinctive behaviors that help develop trust, such as learning that cries will be rewarded with comfort or food.

Month 2

Physical

Limbs relax and stretch partially; lifts head 45 degrees; head wobbly while held sitting; muscle twitches lessen; hands partially unfold; swipes aimlessly; holds rattle briefly.

Language/social

Coos, squeals, and gurgles; smiles responsively; shows emotions, like delight or distress; quiets self with thumb; holds eye contact; studies faces and vaguely mimics facial gestures; tracks moving persons.

Cognitive

Makes associations between behaviors as cues and an elicited response, such as expecting to be held or fed if crying..

Month 3

Physical

Stretches limbs all the way out; holds head about 45 degrees; pushes down on legs when feet are placed on a firm surface; supports upper body with arms when lying on stomach; hands open, makes swiping reaches but still misses more than hits; holds and shakes rattle longer; grabs clothing and hair of others; sucks fingers and fists; plays with hands.

Language/social

Begins to babble, coo, squeal, and gurgle; smiles responsively; shows emotions; enjoys playing with other people and may cry when playing stops. Begins to imitate some sounds, draws out vowel sounds, such as aaah and oooh; makes louder sounds; begins to laugh.

Cognitive

Learns that smiles, cries, and body language cause people to react; learns cause and effect, like hitting mobile will cause it to move. Becomes more expressive and communicates more with face and body.

Month 4

Physical

Stands with support; sits propped on arms and lifts head 90 degrees and scans 180 degrees; rests on elbows; rolls tummy-to-side; uses two-handed embracing reach; accurately gathers dangled toy; explores clothing; uses mitten-like grasp.

Language/social

Shapes mouth to change sounds, blows bubbles; laughs hilariously when tickled, makes motions for attention, such as flapping arms to be picked up; develops better depth perception; gazes intently; tracks accurately.

Cognitive

Forms mental images of what to expect when given a cue; becomes aware that people and things have labels, such as cat or mommy or daddy.

Month 5

Physical

Sits propped with pillows on floor or chair; stands, holding on for balance; rolls purposefully from tummy-to-back; rocks on tummy; assumes push-up position; wiggles forward; cranes neck forward to see; reaches one hand with good aim; transfers toys from hand to hand or mouth; begins block play.

Language/social

Babbles to get attention; mimic sounds, inflection, gestures; watches mouth movements; vocalizes sounds for different needs; may show interest in solid foods; interested in colors.

Cognitive

Learns which sounds and gestures get a response; shows decision-making expressions during hand play; figures out objects and changes hand position to touch objects.

Month 6

Physical

Sits briefly by self; sits in high chair; stands briefly while leaning on furniture; rolls over both ways; digs in with toes and hands to move toward toy; reaches precisely; points at toys; manipulates blocks; uses whole hand to pick up small objects with thumb and fingers.

Language/social

Strings out longer and more varied sounds; experiments with pitch and volume of new sounds and notices reactions they produce; reflects moods by sound and body language; mimics facial gestures better.

Cognitive

Shows more intentionality during play, such as trying to figure out how to pick up a third object with one already in each hand.

http://www.webmd.com/parenting/healthtool-infant-milestones