What to know
Skills such as taking a first step, smiling for the first time, and waving “bye bye” are called developmental milestones. Children reach milestones in how they play, learn, speak, act, and move.
Overview
Download CDC's FREE Milestone Tracker app
Check the milestones your child has reached by 2 months by completing a checklist with CDC's free Milestone Tracker app, for iOS and Android devices.
Click on the age of your child to complete a milestone checklist online:
Content Source
National Center on Birth Defects and Developmental Disabilities (NCBDDD)
About This Page
Published: September 4, 2025
Updated: February 17, 2026
This page was last updated on this date. Updates may include minor edits, image changes, or other modifications to page content.
Reviewed: February 17, 2026
The information on this page was last reviewed by subject matter experts to ensure accuracy.