Why track baby age in weeks?
In the first two years of life, development happens so rapidly that tracking age in weeks — rather than months — gives a much more precise picture. Paediatricians, health visitors, and developmental specialists commonly use weeks-based age, especially during well-baby visits and when screening for developmental concerns.
Developmental milestone overview
| Age | Milestone |
|---|---|
| 4 weeks | Focuses on faces; startles to sound |
| 8 weeks | Social smile appears; follows objects with eyes |
| 12 weeks | Holds head up briefly; coos |
| 16 weeks | Reaches for objects; laughs |
| 24 weeks (6 months) | Sits with support; babbles; rolls both ways |
| 36 weeks (9 months) | Pulls to stand; stranger anxiety; pincer grasp |
| 52 weeks (12 months) | First words; walks with support |
| 18 months | 10–20 word vocabulary; runs; stacks 2 blocks |
| 24 months | Combines 2 words; kicks ball; 50+ words |