Introduction: Why tracking milestones matters
Watching a baby grow during the first year is exciting — and a little stressful. Developmental milestones describe typical skills in how babies play, learn, speak, behave and move. Regularly tracking milestones helps you celebrate progress and spot concerns early so your child can get help if needed.
Use milestone checklists as a conversation starter with your pediatrician, but remember they do not replace formal screening. If you or your child's provider have concerns, ask for a validated developmental screening or referral.
Key milestones by age (high-level overview)
Below are common milestones many infants reach by these age ranges. Every child is unique; these lists indicate what most babies can do and are meant to help you notice patterns over time.
By 2 months
- Smiles at people; begins to coo and make gurgling sounds.
- Follows moving objects with eyes; lifts head briefly when on tummy.
By 4 months
- Babbles and copies some sounds; shows interest in hands and objects.
- Holds head steady; pushes down on legs when feet touch a firm surface.
By 6 months
- Babbles with different sounds; begins to recognize familiar faces and reach for objects.
- Sits with minimal support; may start to roll both directions.
By 9 months
- Uses simple gestures (like shaking head "no"), responds to own name.
- Crawls or moves independently; pulls to stand.
By 12 months
- Says a few single words (e.g., "mama," "dada"), may take first steps.
- Can point to things and plays simple interactive games (peek-a-boo).
These milestone groupings are adapted from CDC resources and are intended to guide parental monitoring. For full age-by-age lists and printable checklists, use CDC’s materials or the Milestone Tracker app.
When to contact a professional — red flags and next steps
Don't wait to act if you notice these signs. A small number of missed milestones can be typical, but certain patterns should prompt a discussion with your child's pediatrician or an early intervention program:
- Loss of skills: If your baby loses a skill they once had (for example, stops babbling or no longer uses gestures), contact a provider right away.
- Little or no social response: Not smiling by 2 months, not watching things move, or not responding to loud sounds.
- Communication concerns: No babbling by 9 months or no single words by 12 months; limited gestures (pointing, waving).
- Motor delays: Not sitting by 9 months or not crawling/pulling to stand when peers do.
Recommended next steps:
- Bring concerns to the pediatrician: Share specific examples, dates, and behaviors. Ask for a formal developmental screening if one hasn’t been done. The AAP recommends standardized developmental screening at 9, 18, and 30 months and autism-specific screening at 18 and 24 months; providers should also screen whenever there is concern.
- Ask about referrals: If screening shows risk, ask about early intervention (IDEA Part C) services, pediatric rehabilitation, or a visit with a developmental pediatrician, audiologist, or speech-language pathologist.
- Contact early intervention directly if needed: Families can contact state or local early intervention systems without waiting for a doctor's referral; early help is most effective when started promptly.
- Keep tracking and documenting: Use a milestone checklist or the CDC Milestone Tracker app to record what you see. Bring this summary to appointments to make conversations efficient.
Early identification and intervention improve long-term outcomes — so trust your parental instincts and act early if you’re unsure.
