Motor Development

Last updated: April 1, 2026
Table Of Contents
  1. Summary of important motor milestones
  2. Overview of motor development
  3. Motor development

Summary of important motor milestones

AgeMilestones
1 month oldRaise their head off the table
2 months oldHolds their head steady while sitting on the lap
4 months oldLifts head above plane; grasp objects; 2x birthweight
6 months oldTransfers objects from hand to hand; primitive motor reflexes gone
8 months oldPincer grasp; crawling; rolling over
1 year oldCruising; stands on own; 3x birthweight
15 months oldWalking
16 months oldScribble with a crayon; build a tower of 2 or 3 blocks
18 months oldRuns awkwardly; builds a tower of 4 blocks
2 years oldRuns normally; crawls stairs; builds a tower of 7 blocks
2.5 years oldAscends stairs with alternating feet; stands on one foot; 4x birthweight
3 years oldDescends stairs with alternating feet; copies a circle
4 years oldCopies a square; hops
5 years oldCopies a triangle

Overview of motor development

Motor development involves functional and myelinated neuron development, proprioceptive development, and muscular strength.

Definition of terms

TermDefinition
Developmental coordination disorder (dyspraxia)Marked impairment in the acquisition and execution of coordinated motor skills, resulting in performance that is substantially below that expected for the individual’s chronological age and opportunities for skill learning. It significantly interferes with activities of daily living and occurs in the absence of intellectual disability or neuromuscular conditions affecting movement. It may present with clumsiness and incoordination.

Disorders that lead to a delay or inability to attain motor milestones (or regression of motor milestones)

CategoryDisorders
Disorders of neuronal functionCerebral palsy, traumatic brain injury, hypoxic-ischaemic brain injury, Rett syndrome
Myelin disordersNiemann-Pick disease, Tay-Sachs disease, Krabbe’s disease, Gaucher’s disease, Metachromatic leukodystrophy
Disorders of muscular strengthMuscular dystrophy

Motor development

  • Neonate
    • Tends to lie in a flexed position; will turn the head from side to side
    • Some head sagging on horizontal suspension (the neonate should not be hypotonic)
    • All primitive reflexes are present (Moro, grasp, rooting, tonic neck, etc.)
    • By 1 month of age, the head should raise off the table (head sagging is decreased)
    • When the head is manipulated, the infant will not maintain contact (”doll’s eyes”)
    • Should reattain birthweight by 2 weeks of age, and grow 30g/day until 4 months
  • 2 months
    • Head lag gone (head and trunk held in the same plane on horizontal suspension)
    • Should be able to hold head steady while sitting in lap
    • Should be able to raise head slightly when lying in the prone position (tummy time is important to develop neck tone)
  • 4 months of age
    • An infant should be able to lift the head above the plane when held in horizontal suspension
    • An infant should be able to grasp objects like a rattle (and may reach for objects held above him/her as visual acuity improves)
    • Primitive reflexes may begin to disappear (may manipulate objects with both hands as the palmar grasp reflex disappears, able to inspect hands at midline – hand obsessed)
    • Infants show more purposeful motor activity
    • Growth slows to 20 g/day until 1 year of age; birthweight should have doubled
  • 6 months of age
    • Infants should be able to sit up without support
    • May be able to roll over and crawl
    • Primitive reflexes should be gone
    • An infant should be able to transfer objects from hand to hand
  • 8 months of age
    • Should be able to sit up straight without support
    • An infant should be able to crawl and roll over
    • Pincer grasp develops
    • An infant can walk with assistance (holding one or both hands/arms)
    • Baby will often “cruise” (which helps the baby develop muscle strength for walking)
  • 12 months of age
    • Birthweight should have tripled by the first birthday; length increased by 50%; head circumference increased by 10cm
    • An infant can stand on his/her own
    • An infant is cruising by this point (able to walk with one hand held)
    • Able to turn pages of a book (hand-eye coordination)
  • 16 months of age
    • A child should be walking by 15 months of age, and can run (albeit awkwardly)
    • A child can crawl up a stair(s)
    • Should be able to scribble with a crayon
    • Classically, by 16 months, the child should be able to build a tower of 2 or 3 blocks (reflects gross and fine motor development)
  • 18 months of age (1.5 years)
    • A child should be able to run by this point
    • Should be able to walk up and down stairs with hands held (with alternating steps)
    • Often will be able to sit on a small, child-sized chair
    • Classically, one should be able to build a tower of 4 blocks
  • 24 months of age (2 years old)
    • Development of coordination
    • Should be able to jump in place
    • Often able to insert small objects into holes
    • Classically, one should be able to build a 7-block tower
  • 30 months of age (2.5 years)
    • Birth weight should have quadrupled
    • A child should be able to properly ascend stairs with alternating feet
    • A child should be able to stand on one foot
  • 3 years of age
    • A child should be able to descend the stairs with alternating feet
    • Should be able to properly draw or copy a circle
    • Left– or right-handedness is developed
    • Should be able to ride a tricycle if trained
  • 4 years
    • A child should be able to hop in place
    • Should be able to throw overhand
    • Should be able to copy a square
Reference Intervals ›
Biochemistry
ACTHP: <80 ng/L
ALTP: 5–35 U/L
AlbuminP: 35–50 g/L
AldosteroneP: 100–500 pmol/L
Alk. phosphataseP: 30–130 U/L
α-AmylaseP: 0–180 IU/dL
α-FetoproteinS: <10 kU/L
Angiotensin IIP: 5–35 pmol/L
ADHP: 0.9–4.6 pmol/L
ASTP: 5–35 U/L
BicarbonateP: 24–30 mmol/L
BilirubinP: 3–17 μmol/L
BNPP: <50 ng/L
CRPP: <10 mg/L
CalcitoninP: <0.1 mcg/L
Calcium (ionized)P: 1.0–1.25 mmol/L
Calcium (total)P: 2.12–2.60 mmol/L
ChlorideP: 95–105 mmol/L
CholesterolP: <5.0 mmol/L
VLDLP: 0.128–0.645 mmol/L
LDLP: <2.0 mmol/L
HDLP: 0.9–1.93 mmol/L
Cortisol AMP: 450–700 nmol/L
Cortisol MidnightP: 80–280 nmol/L
CK ♂P: 25–195 U/L
CK ♀P: 25–170 U/L
CreatinineP: 70–100 μmol/L
FerritinP: 12–200 mcg/L
FolateS: 2.1 mcg/L
FSHP: 2–8 U/L ♂; >25 menopause
GGT ♂P: 11–51 U/L
GGT ♀P: 7–33 U/L
Glucose (fasting)P: 3.5–5.5 mmol/L
Growth hormoneP: <20 mu/L
HbA1C (DCCT)B: 4–6%
HbA1C (IFCC)B: 20–42 mmol/mol
Iron ♂S: 14–31 μmol/L
Iron ♀S: 11–30 μmol/L
Lactate (venous)P: 0.6–2.4 mmol/L
Lactate (arterial)P: 0.6–1.8 mmol/L
LDHP: 70–250 U/L
LHP: 3–16 U/L
MagnesiumP: 0.75–1.05 mmol/L
OsmolalityP: 278–305 mosmol/kg
PTHP: 0.8–8.5 pmol/L
PotassiumP: 3.5–5.3 mmol/L
Prolactin ♂P: <450 U/L
Prolactin ♀P: <600 U/L
PSAP: 0–4 mcg/mL
Protein (total)P: 60–80 g/L
Red cell folateB: 0.36–1.44 μmol/L
Renin (erect)P: 2.8–4.5 pmol/mL/h
Renin (recumbent)P: 1.1–2.7 pmol/mL/h
SodiumP: 135–145 mmol/L
TBGP: 7–17 mg/L
TSHP: 0.5–4.2 mU/L
T4P: 70–140 nmol/L
Free T4P: 9–22 pmol/L
TIBCS: 54–75 μmol/L
TriglyceridesP: 0.50–2.3 mmol/L
T3P: 1.2–3.0 nmol/L
Troponin TP: <0.1 mcg/L
Urate ♂P: 210–480 μmol/L
Urate ♀P: 150–390 μmol/L
UreaP: 2.5–6.7 mmol/L
Vitamin B12S: 0.13–0.68 nmol/L
Vitamin DS: 50 nmol/L
Arterial Blood Gases
pH7.35–7.45
PaCO₂4.7–6.0 kPa
PaO₂>10.6 kPa
Base excess±2 mmol/L
Urine
Cortisol (free)<280 nmol/24h
Hydroxyindole acetic acid16–73 μmol/24h
Hydroxymethylmandelic acid16–48 μmol/24h
Metanephrines0.03–0.69 μmol/mmol cr.
Osmolality350–1000 mosmol/kg
17-Oxogenic steroids ♂28–30 μmol/24h
17-Oxogenic steroids ♀21–66 μmol/24h
17-Oxosteroids ♂17–76 μmol/24h
17-Oxosteroids ♀14–59 μmol/24h
Phosphate (inorganic)15–50 mmol/24h
Potassium14–120 mmol/24h
Protein<150 mg/24h
Protein/creatinine ratio<3 mg/mmol
Sodium100–250 mmol/24h
Haematology
WCC4.0–11.0 ×10⁹/L
RBC ♂4.5–6.5 ×10¹²/L
RBC ♀3.9–5.6 ×10¹²/L
Hb ♂130–180 g/L
Hb ♀115–160 g/L
PCV ♂0.4–0.54 L/L
PCV ♀0.37–0.47 L/L
MCV76–96 fL
MCH27–32 pg
MCHC300–360 g/L
RDW11.6–14.6%
Neutrophils2.0–7.5 ×10⁹/L (40–75%)
Lymphocytes1.0–4.5 ×10⁹/L (20–45%)
Eosinophils0.04–0.44 ×10⁹/L (1–6%)
Basophils0–0.10 ×10⁹/L (0–1%)
Monocytes0.2–0.8 ×10⁹/L (2–10%)
Platelets150–400 ×10⁹/L
Reticulocytes0.8–2.0% / 25–100 ×10⁹/L
Prothrombin time10–14 s
APTT35–45 s
Paediatric
Pulse Rate (bpm)
Neonate140–160
Infant <1yr120–140
1–5 years110–130
5–12 years80–120
>12 years70–100
Respiratory Rate (tachypnoea)
0–2 months≥60/min
2–12 months≥50/min
1–5 years≥40/min
>5 years≥30/min
Blood Pressure (mmHg)
Term65/45
1 year75/50
4 years85/60
8 years95/65
10 years100/70
Weight Formulas
3–12 months(a + 9)/2 kg
1–6 years2a + 8 kg
>6 years(7a − 5)/2 kg
Haemoglobin (g/dL)
Term newborn13–20
1 month11–18
2 months10–15
1–2 years10–13
>2 years11–14
MUAC (6 months–5 years)
Obese>17.5 cm
Normal13.5–17.4 cm
At risk12.5–13.4 cm
Moderate malnutrition11.5–12.4 cm
Severe malnutrition<11.5 cm
Developmental Milestones
Social smile1.5 months
Head control4 months
Sits unsupported7 months
Crawls10 months
Stands unsupported10–12 months
Walks12–13 months
Talks18 months
CSF WBC (/mm³)
Term newborn0–25
>2 weeks0–5
Calculator ›

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