As a parent, how do you know whether your child is walking, speaking or learning to make friends at the right age? Most of us would rely on something called developmental milestones, where resources can be easily found online or through your healthcare professional. Earlier this year, the American Academy of Pediatrics and the US Centers for Disease Control introduced new ages and milestones into the checklist, and launched a Milestone Tracker App for parents. We ask consultant developmental paediatrician Dr Rajini Sarvananthan what the revised milestones mean for parents and children, and how to use the CDC app.

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