Babies Ltd only publishes what official sources say:
- Milestones: quoted from the CDC's "Learn the Signs. Act Early." checklists. CDC, "Learn the Signs. Act Early." milestone checklists.
- Movement timing ranges: the WHO Motor Development Study. WHO Multicentre Growth Reference Study Group, "WHO Motor Development Study: Windows of achievement for six gross motor development milestones," Acta Paediatrica 95 (2006): 86-95.
- Growth percentiles: the WHO growth standards data files published by the CDC, which the CDC recommends for children under 2. CDC, WHO growth standards data files (birth to 24 months); CDC, "Using WHO Growth Standard Charts".
- Solid foods: CDC, "When, What, and How to Introduce Solid Foods" (updated Apr 14, 2026). Teeth: American Dental Association (MouthHealthy), "Eruption Charts".
Not medical advice. We explain what the charts and checklists say; we cannot assess your child. If you have any concern, talk with your child's doctor. Checked October 17, 2026.