Parenting
Baby Developmental Milestones by Month: Your Baby's First Year
General CDC developmental milestones at the 2, 4, 6, 9, and 12-month checkpoints, across motor, language, social, and cognitive skills — and what actually counts as a reason to check in early.
The CDC tracks infant development at five checkpoints in the first year — 2, 4, 6, 9, and 12 months — across four areas: motor skills, language and communication, social-emotional skills, and cognitive development. A milestone is defined as something about 75% of children do by a given age, so it's a general guide, not a pass-fail test, and premature babies are typically tracked by their adjusted (due-date-based) age rather than birth date for the first couple of years. The clearest reasons to ask your pediatrician for a developmental screening are missing several milestones for their age, or losing a skill they'd already gained — that second one matters more than hitting an exact date.
Milestone lists get treated like report cards, and that's the wrong way to read them. They're closer to a loose map: general markers that most babies pass at roughly similar times, useful mainly for noticing a pattern worth mentioning at a well-check, not for scoring a single afternoon.
How to actually use a milestone list
The CDC's own "Learn the Signs. Act Early." program builds its checklists around one useful definition: a milestone is something about 75% of children can do by a given age. That framing matters — it means a quarter of typically developing babies are still working on any given skill past the "expected" age, which is normal, not a red flag on its own. What's below is a general, illustrative summary at each checkpoint, not the full clinical checklist; the CDC's complete, downloadable checklists (linked in sources) go further.
The five checkpoints
| Checkpoint | Motor | Language & social |
|---|---|---|
| 2 months | Holds head up briefly during tummy time; follows a face or object with their eyes | Calms down when spoken to or picked up; starts to smile at people |
| 4 months | Pushes up onto forearms during tummy time; brings hands to mouth | Babbles with expression; smiles on their own to get your attention |
| 6 months | Rolls over in at least one direction; begins to sit with support | Responds to their own name; makes sounds back and forth ("talking") with you |
| 9 months | Sits without support; moves things from one hand to the other | Plays peekaboo; looks when you point at something |
| 12 months | Pulls to stand; may take a few steps holding onto furniture | Waves bye-bye; tries to say one or two words besides "mama"/"dada" |
This is a summary, not the full checklist
This table is meant to be a quick, general reference. The CDC's actual checklists include more items per age and cover cognitive skills separately — worth pulling up directly if you want the complete list for your baby's exact age (linked below).
If your baby was born early
For babies born preterm, milestones are typically tracked using adjusted age — your baby's age counted from their original due date rather than their actual birth date — through about the first two years. A baby born eight weeks early who isn't yet rolling at the 6-month mark on the calendar may be exactly on track for their 4-month adjusted age. This is standard, expected practice, not a workaround; ask your pediatrician which age they're using when discussing your baby's development.
When to act early
- Not meeting several milestones expected for their age, especially across more than one area (motor, language, social)
- Losing a skill they used to have — this is a stronger signal than being late to a new one
- No response to loud sounds, or not startling, by 2-3 months
- No babbling or back-and-forth sounds by 9 months
- Not pointing at things, or not responding to their name, by 12 months
- Any concern that keeps nagging at you, even without a specific milestone attached to it
The CDC's guidance is explicit that "wait and see" isn't the safer choice — acting early, through your pediatrician or a state early-intervention program, is what actually helps, and evaluations through early intervention are typically free regardless of insurance status.
Past 12 months
This first-year overview stops at 12 months on purpose — our toddler speech milestones guide picks up the language side specifically at 18 months, 2 years, and 3 years, which is where a lot of the more detailed, talkable milestones start to show up. If sleep has gotten rocky right around one of these developmental leaps, that's common — our guide to sleep regressions by age explains why a new skill so often disrupts sleep for a few weeks.
Frequently Asked Questions
What if my baby is behind on one thing but ahead on another?
Very common, and not usually a concern on its own — babies rarely develop every area at an even pace. A baby who's an early talker but a later walker, or vice versa, is a normal pattern. It's a broader cluster of missed milestones across areas, or a lost skill, that's worth flagging.
Are 'app' milestone trackers as reliable as the CDC checklist?
Many are based on the same underlying research, but they vary in quality and some set expectations more aggressively than the CDC does, which can cause unnecessary worry. The CDC's own checklist is free, downloadable, and a reliable baseline to compare against if an app has you concerned.
My pediatrician didn't mention a screening at our last visit — should I ask for one?
Yes, you can ask directly. The AAP recommends developmental screening at specific well-visits (commonly around 9, 18, and 30 months, plus autism-specific screening around 18 and 24 months), but you don't need to wait for a scheduled screening if you have a concern now.
Does more screen time slow down development?
The concern isn't screens in isolation so much as screens replacing the face-to-face interaction that builds language and social skills at this age. [Our guide to screen time by age](/parenting/screen-time-guidelines-by-age) covers what the AAP actually recommends for children under 2.
Sources & Further Reading
- CDC's Developmental Milestones — Centers for Disease Control and Prevention (Learn the Signs. Act Early.) (reviewed 2026-08-14)
- Milestone Checklists by Age — Centers for Disease Control and Prevention (Learn the Signs. Act Early.) (reviewed 2026-08-14)
Related Guides
Toddler Speech Milestones by Age: What's Normal, and When to Act Early
General CDC speech and language milestones for 18 months, 2, and 3 years — plus the clear signs it's worth asking your pediatrician about a hearing and developmental check.
Baby and Toddler Sleep Regressions by Age: What's Happening at 4, 8, and 18 Months
Why sleep suddenly falls apart at 4 months, 8 months, and around 18 months, what's actually driving each one developmentally, and what to do differently (and not differently) at each stage.
Age-Appropriate Chores for Kids
Age-by-age chore ideas for toddlers through school-age kids, plus how to handle allowance and what to do when a chore chart stops working.
"Is This Normal?" 10 Newborn Behaviors That Surprise New Parents
The startling-but-normal things newborns do — from noisy breathing to "newborn blindness" — and the few real red flags that mean call your pediatrician.
Mom's Magazine Editorial Team
Editorial Team
The Mom's Magazine editorial team researches and writes practical, plainly-sourced guidance for parents and families. Guides are reviewed for accuracy and updated as recommendations change. Where a topic calls for professional expertise, we cite reputable organizations and, for health topics, add a qualified reviewer before publishing.
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