Sources behind the timeline
These are the guidance pages and research papers behind the timeline. Open a source to read more about a topic or see how a recommendation was developed.
“Checked” records when the relevant source material was compared with our wording. It is an editorial check, not clinical approval. Links open external pages, which may have changed since that date. The country shown helps you identify local guidance.
All sources
Infant Vision Development: What Can Babies See?
Parent-facing paediatric guidance on the close focal range, blurry distance vision, faces, movement and rapidly developing visual coordination in early infancy.
Faltering growth: recognition and management of faltering growth in children
Clinical recommendations for expected early weight loss, birthweight regain and when assessment or feeding support is indicated.
Developmental follow-up of children and young people born preterm
UK-specific clinical guidance defining preterm birth as before 37+0 weeks and supporting corrected-age use for developmental assessment up to 2 years.
Speech and Language Developmental Milestones
Official hearing and communication guidance covering familiar voices, early sound responses, gestures, simple directions, books and emerging word combinations.
Helping your baby to sleep
Age-banded sleep guidance that emphasises individual variation and normal waking.
Your baby's weight and height
Explains centile trajectories, routine weighing intervals and the gradual slowing of weight gain after the first six months.
Breastfeeding: the first few days
Early breastfeeding guidance covering frequent feeding, a rough 8-to-12-or-more daily guide and early feeding cues.
Cluster feeding
Describes temporary periods of closely grouped feeds during the broad first three to four months without assigning fixed weeks.
Soothing a crying baby
Practical crying guidance stating that crying tends to increase from around 2 weeks and gradually reduce around 3 months, plus soothing ideas and routes to urgent help.
Overdue – have you gone past your due date?
Explains that the expected due date estimates when pregnancy reaches 40 weeks. Used only to validate the corrected-age date input, not to predict an individual birth.
Baby and toddler play ideas and early learning
Everyday talking, play, reading and responsive interaction ideas.
Your baby's first solid foods
Age-banded guidance for readiness, early tastes and textures, meals alongside milk and family eating after 12 months.
First words and little sentences: 1 to 2 years
Talking, books and pretend-play ideas for the second year. Activities are suggestions, not tests.
Getting to know your newborn
Explains that newborns can see but their vision is not yet well focused and develops gradually over the first months.
Feeding on demand
Responsive and paced bottle-feeding guidance centred on hunger, pause and fullness cues rather than a clock.
Sudden infant death syndrome (SIDS)
UK safer-sleep guidance, including back sleeping, a clear cot, room sharing and situations in which bed sharing is unsafe.
Your baby's sleep patterns
Describes very wide newborn sleep totals and sleep arriving in bursts across the full day.
Help your toddler manage emotions
Guidance on growing frustration around toddlerhood and helping children regulate, relate and then reason.
Crying in the first 12 months of life: a systematic review and meta-analysis of cross-country parent-reported data and modeling of the ‘cry curve’
Pooled crying-duration trajectories whose models place the broad early high point around 4 to 8 weeks, with substantial variation between studies and settings.
2 Month Online Milestone Checklist
The checklist overview says to use corrected age when a child was born more than 3 weeks prematurely.
Milestone Moments booklet
Full 60-page booklet with age-specific milestone checklists and everyday activities from 2 months through 5 years.
Developmental Milestones: Key Points
Defines milestone checklists as things most children (75% or more) can do by an age. Not diagnostic tools or standards.
Infant and young child feeding
Global complementary-feeding guidance covering gradual variety and responsive attention to hunger and fullness.
Child growth standards: length velocity
Growth-velocity standards intended for interpreting change across measurement intervals.
WHO Motor Development Study: windows of achievement for six gross motor development milestones
The original study behind the motor windows. Some children in the study never showed hands-and-knees crawling.
Windows of achievement for six gross motor development milestones
Table used for the lower and upper age ranges shown in the timeline.
WHO Motor Development Study: windows of achievement for six gross motor milestones
Population windows for sitting, crawling, standing and walking. These are broad achievement windows, not deadlines.
Guidelines on physical activity, sedentary behaviour and sleep for children under 5 years of age
WHO sleep recommendations, including naps. The publication page links to the guideline; these are recommended totals rather than observed averages.
Nurturing care for early childhood development
Global framework for responsive caregiving, safety, health, nutrition and early learning.