[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Behavioral science](https://durgical.com/en/behavioral-science/) › [Human development across the life span](https://durgical.com/en/behavioral-science/areas/development/) › Developmental milestones: domains, corrected age and red flags

# Developmental milestones: domains, corrected age and red flags

- Concept

Milestones are skills most children reach by a given age; they are tracked by domain, with corrected age for preterm babies, and any concern is evaluated.

Updated Nov 5, 2026

## Key points

- CDC 2022 checklists: each milestone is reached by 75 % or more of children at that age (older lists used the average, 50 %); 15- and 30-month checklists were added.
- Surveillance at every well-child visit; standardized general developmental screening at 9, 18 and 30 months; autism-specific screening at 18 and 24 months.
- Corrected age = chronological age minus the weeks born early; used for preterm infants, usually until about 2 years.
- Loss of a skill already gained (regression) is a red flag at any age.
- Global delay (two or more domains) versus isolated delay (one domain) points to different causes.
- A missed milestone is a reason to screen and evaluate, not a diagnosis; any language delay needs a hearing test.

## What it is

A developmental milestone is a skill, such as smiling, walking or naming objects, that most children show by a certain age. Development is followed in domains (gross motor, fine motor, language and communication, social-emotional and cognitive) because a delay can affect one domain or several. Since the 2022 revision, the CDC checklists list skills that at least 75 % of children reach by each age, so a missed milestone is a reason to act early rather than to wait and see.

## Key facts

- Monitoring is the ongoing, informal tracking of milestones by families and clinicians; screening uses a validated tool at set ages or whenever there is a concern.
- Generic screening tools include parent-completed developmental questionnaires and autism-specific parent questionnaires; CDC's free milestone checklists support monitoring, not diagnosis.
- Development has a sequence (head to toe, center to periphery, gross before fine), but the timing varies between children and cultures.
- Parental concern is a valid reason to screen, even when the child seems to be on track in the office.

## The domains of development and what each tracks

| Domain | What it tracks | Example |
| --- | --- | --- |
| Gross motor | Posture and large-muscle movement | Head control, sitting, walking, hopping |
| Fine motor | Hand use and eye-hand coordination | Transferring objects, pincer grasp, drawing |
| Language and communication | Understanding (receptive) and producing (expressive) language, gestures | Babbling, pointing, first words, sentences |
| Social-emotional | Relationships, emotions and play | Social smile, stranger wariness, pretend play |
| Cognitive | Learning, thinking and problem-solving | Looking for a hidden toy, using objects correctly |

## Clinical notes

- Red flags that call for prompt evaluation: regression, hand preference in the first year, persistent primitive reflexes, asymmetry of movement, no response to sound or name.
- Common causes of delay to keep in mind: prematurity, hearing or vision loss, genetic syndromes, cerebral palsy, autism, under-nutrition and an understimulating or neglectful environment.
- Early intervention works best when started early: a delay found at 9 months is easier to support than one found at school entry.

## Memory aid

Five boxes on every visit: Big moves, Small hands, Words, Friends, Thinking. Lost a box? Act now.

## Test yourself

Think of the answer, then tap the question to see it.

## What percentage of children reach a milestone by the age listed on the revised CDC checklists?

At least 75 %. Older lists used the average age (50 %), so the new ages are a little later and a missed milestone is more meaningful.

## How is corrected age calculated for a baby born at 32 weeks who is now 6 months old?

Subtract the 8 weeks born early from the chronological age: about 4 months corrected. It is used for preterm infants, usually until about 2 years.

## At what ages is general developmental screening recommended, and when is autism-specific screening done?

General screening at 9, 18 and 30 months; autism-specific screening at 18 and 24 months, plus surveillance at every visit.

## Which developmental finding is a red flag at any age?

Loss of skills the child already had (regression). It needs prompt evaluation.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/behavioral-science/developmental-milestones-domains-corrected-age-and-red-flags/)

## Elsewhere in DurgiPedia

- [Pediatric history: perinatal, growth, development and vaccines](https://durgical.com/en/clinical-exam/pediatric-history-perinatal-growth-development-and-vaccines/)
- [Newborn physiology and fetal maturation](https://durgical.com/en/physiology/newborn-physiology-and-fetal-maturation/)

## Connections

## Related 7

- [Milestones of the first year](https://durgical.com/en/behavioral-science/milestones-of-the-first-year/)
- [Milestones from 1 to 3 years](https://durgical.com/en/behavioral-science/milestones-from-1-to-3-years/)
- [Milestones from 4 years to school age](https://durgical.com/en/behavioral-science/milestones-from-4-years-to-school-age/)
- [Primitive reflexes and when they disappear](https://durgical.com/en/behavioral-science/primitive-reflexes-and-when-they-disappear/)
- [Language development and speech red flags](https://durgical.com/en/behavioral-science/language-development-and-speech-red-flags/)
- [Piaget's stages of cognitive development](https://durgical.com/en/behavioral-science/piaget-s-stages-of-cognitive-development/)
- [Screening questionnaires in primary care](https://durgical.com/en/behavioral-science/screening-questionnaires-in-primary-care/)

## Related conditions 8

- [Failure to thrive (faltering growth)](https://durgical.com/en/conditions/failure-to-thrive/)
- [Autism spectrum disorder (ASD)](https://durgical.com/en/conditions/autism-spectrum-disorder/)
- [Cerebral palsy](https://durgical.com/en/conditions/cerebral-palsy/)
- [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/)
- [Hearing loss (conductive and sensorineural, including sudden hearing loss)](https://durgical.com/en/conditions/hearing-loss/)
- [Prematurity and its complications](https://durgical.com/en/conditions/prematurity-and-its-complications/)
- [Fragile X syndrome](https://durgical.com/en/conditions/fragile-x-syndrome/)
- [Rett syndrome](https://durgical.com/en/conditions/rett-syndrome/)

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Educational content on behavior and the clinical relationship; not a diagnostic or treatment guide and no substitute for assessment by a health professional. If you or someone near you is at risk, seek help now from an emergency service or a mental-health helpline.

Sources: [CDC's Developmental Milestones](https://www.cdc.gov/act-early/milestones/index.html) (Centers for Disease Control and Prevention (CDC), 2026); [About Learn the Signs. Act Early.](https://www.cdc.gov/act-early/about/index.html) (Centers for Disease Control and Prevention (CDC), 2025); [Clinical Screening for Autism Spectrum Disorder](https://www.cdc.gov/autism/hcp/diagnosis/screening.html) (Centers for Disease Control and Prevention (CDC), 2025).

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Source: https://durgical.com/en/behavioral-science/developmental-milestones-domains-corrected-age-and-red-flags/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/behavioral-science/developmental-milestones-domains-corrected-age-and-red-flags/