Baby Milestones Month by Month

What changed in 2022, and why it matters

If you are comparing your baby against a chart you found online, check its date. The CDC's "Learn the Signs. Act Early." milestone checklists were rewritten and republished in February 2022, and the change was substantial enough that older lists give different answers.

The old checklists placed milestones at the age when about half of children reached them. The new ones place each milestone "at ages by which at least 75% of children would be expected to exhibit them, in an effort to make even one missing milestone more 'actionable' (likely to prompt screening and possible referral)". The CDC states the reasoning plainly: "With a milestone at 50%, half of all children would still reasonably be expected to have not yet achieved it. This change is intended to reduce the 'wait and see' approach often taken when a child is missing an average age milestone."

So the current checklists are deliberately not averages. They describe what most babies do, which is why a missing one is worth mentioning rather than something to panic about or ignore.

One more thing the CDC says that almost nobody repeats: "The developmental milestones included on CDC's milestone checklists are not developmental guidelines or standards for children's development. They should not be used as screening or diagnostic tools to detect developmental delays." They are conversation starters for appointments you already have.

What is normal, month by month

By 2 months

Calms down when spoken to or picked up; looks at your face; seems happy to see you; smiles when you talk or smile. Makes sounds other than crying, and reacts to loud sounds. Watches you as you move and looks at a toy for several seconds. Holds head up when on tummy, moves both arms and both legs, and opens hands briefly.

By 4 months

Smiles on their own to get your attention; chuckles, not yet a full laugh; looks, moves or makes sounds to keep your attention. Coos with "oooo" and "aahh" sounds, makes sounds back when you talk, and turns towards your voice. Opens their mouth at the sight of breast or bottle when hungry, and looks at their hands with interest. Holds head steady without support when you hold them, holds a toy placed in their hand, swings at toys, brings hands to mouth, and pushes up onto elbows or forearms on their tummy.

By 6 months

Knows familiar people, likes looking at themselves in a mirror, and laughs. Takes turns making sounds with you, blows raspberries, and squeals. Puts things in their mouth to explore them, reaches for a toy they want, and closes their lips to show they do not want more food. Rolls from tummy to back, pushes up with straight arms on their tummy, and leans on their hands to support themselves sitting.

By 9 months

Shy, clingy or fearful around strangers; shows several facial expressions; looks when you call their name; reacts when you leave; smiles or laughs at peek-a-boo. Makes strings of sounds like "mamamama" and "bababababa", and lifts arms to be picked up. Looks for objects dropped out of sight and bangs two things together. Gets to a sitting position by themselves, sits without support, moves things from hand to hand, and rakes food towards themselves with their fingers.

By 1 year

Plays games with you, like pat-a-cake. Waves bye-bye, calls a parent "mama" or "dada" or another special name, and understands "no" by pausing briefly or stopping. Puts something into a container and looks for things they see you hide. Pulls up to stand, walks holding on to furniture, drinks from a cup without a lid as you hold it, and picks things up between thumb and pointer finger.

Babies born prematurely

A baby born eight weeks early is developmentally eight weeks younger than the calendar says, and comparing them to a term chart will make normal development look like a delay. The NHS is explicit: "If your baby was born prematurely, their developmental age will be calculated from your original due date, not from the actual date they were born, until they are 2 years old." Work out where your baby actually sits with our adjusted age calculator before reading any of the lists above.

What is not just variation

Two things move a missed milestone from "give it time" to "raise it now". The first is a skill your baby had and has stopped doing — the CDC asks families directly, "Has your baby lost any skills he/she once had?" The second is your own unease. The CDC's phrasing is worth keeping: "You know your child best. Don't wait."

When to speak to a health visitor or doctor

In the UK you already have the appointments. The NHS offers a new baby review within 10 to 14 days, a physical examination at six to eight weeks, a nine-to-twelve-month review and a review at two to two-and-a-half years. Before the nine-to-twelve-month and two-year reviews you will be sent an Ages and Stages Questionnaire (ASQ-3) to complete at home. Bring the red book and bring your questions.

Contact a health visitor or GP between reviews if your baby is not doing something on the list for their age, has lost a skill, or if anything is nagging at you. The next step after a concern is developmental screening or referral, not reassurance and a wait.

What actually helps

The CDC's own tips are unglamorous and consistent across every age: respond to your baby's sounds and take turns "talking"; talk, read and sing every day; give floor time and safe things to reach for; name what your baby is looking at; and keep routines for sleeping and feeding. It also says something that belongs here: "You will not spoil your baby by holding or responding to him."