Baby Development Month by Month
Medically reviewed by Safi Ullah Khan
Medically reviewed by Safi Ullah Khan · Written by Muneeb Rana · Last updated 21 October 2026
Quick answer: Baby development month by month: most babies smile socially by 2 months, laugh and roll by 6 months, sit and babble 'mamama' by 9 months, and wave and pull to stand by 12 months, according to CDC checklists. Ranges are wide; talk to your pediatrician early if you're concerned or your baby loses skills.
TL;DR
- CDC checklists exist for 2, 4, 6, 9 and 12 months.
- Each list shows skills 75% of babies have by that age.
- Act early: mention concerns, don't wait.
This guide to baby development month by month covers what babies often do at each age in the first year, how growth compares with WHO standards and simple ways to play together.
Baby milestones by month
| Age | Often seen | Also common | CDC checklist |
|---|---|---|---|
| 1-month-old | lifts head briefly during tummy time | focuses on faces about 8-12 inches away | No |
| 2-month-old | smiles when you talk to them | makes sounds other than crying | Yes |
| 3-month-old | holds head steadier | brings hands to mouth | No |
| 4-month-old | smiles to get your attention, chuckles | coos and makes sounds back | Yes |
| 5-month-old | rolls front to back, often | reaches for and grabs toys | No |
| 6-month-old | knows familiar people | laughs | Yes |
| 7-month-old | sits with less support | transfers toys hand to hand | No |
| 8-month-old | may crawl, scoot or roll to get around | pulls toward standing (some) | No |
| 9-month-old | is shy, clingy or fearful around strangers | looks when you call their name | Yes |
| 10-month-old | pulls to stand and cruises furniture | uses pincer grasp | No |
| 11-month-old | stands alone briefly | may take first steps | No |
| 12-month-old | waves bye-bye | calls a parent 'mama', 'dada' or another special name | Yes |
How milestone checklists work
In 2022 the CDC and AAP updated the milestone checklists so each lists skills that 75% of children show by that age, which means missing one is a reason to talk to your pediatrician rather than to wait and see. Check your baby with the milestone checker. Born early? Use the corrected age calculator.
Growth in the first year
Most babies double their birth weight by around 4-5 months and roughly triple it by 12 months. Growth is checked against WHO growth standards for children under 2, as the CDC recommends. See average baby weight by month and the growth percentile calculator.
Play and development
Talking, reading, tummy time, floor play and responding to your baby's cues support development more than any special toy. Short, frequent moments count.
Tracking growth in Tot
Log weight and height in Tot to see growth charts over time, alongside feeds, sleep, diapers, vaccines and medicines. See the growth chart tracker.
Related: baby feeding chart by month · baby sleep schedule by age · how to read a growth chart · newborn checkup schedule
Download Tot free on the App Store or Google Play. Free with ads; optional Premium.
Sources
- CDC: Developmental Milestones (Learn the Signs. Act Early.): www.cdc.gov (accessed 21 October 2026)
- AAP HealthyChildren.org: Developmental Milestones, 1 Month: www.healthychildren.org (accessed 21 October 2026)
- WHO: Weight-for-age standards: www.who.int (accessed 21 October 2026)
- CDC: WHO Growth Charts for children under 2: www.cdc.gov (accessed 21 October 2026)
- AAP HealthyChildren.org: Corrected Age for Preemies: www.healthychildren.org (accessed 21 October 2026)
Medical disclaimer:
Tot and this website give general information only. Feeding, sleep and growth ranges vary; always follow your pediatrician's advice. If your baby is unwell, contact your doctor or emergency services.
FAQ
What are the major baby milestones by month?
Social smile by 2 months, holding the head steady by 4, rolling and laughing by 6, sitting and babbling by 9, waving and pulling to stand by 12 (CDC).
When should I worry about missed milestones?
Talk to your pediatrician if your baby misses a milestone for their age, loses skills, or you have any concern.
Do premature babies hit milestones later?
They're usually assessed by corrected age until about 2-3 years (AAP).
When do babies double their birth weight?
Around 4-5 months for many babies, though it varies.
Does Tot track milestones?
Tot tracks feeds, sleep, diapers, growth, vaccines and medicines. [CONFIRM: milestone logging]
Related guides
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