• Clinical science

Child development and milestones


Charting an infant or child's growth and development plays an important role in the monitoring of pediatric health and is therefore an important tool of pediatric screening. Several parameters factor in to the assessment, including weight-for-age, height-for-age, and developmental milestones. Developmental milestones are physical and behavioral skills that children with normal development are expected to reach at certain ages. The main domains of developmental milestones include gross motor, fine motor, language, cognitive, social, and self-care skills. Developmental regression and the persistence of primitive reflexes are indicators of global developmental delay. Failure to thrive (FTT) is defined as inadequate physical growth of a child for its age. The most common cause is wrong infant nutrition and feeding practices. Assessment of health and development is typically performed during well-child examinations, which ensure timely detection of underlying diseases and enable early intervention to help minimize mortality and disability.

Primitive reflexes

Definition: : Reflexes that are normally present in infancy and early childhood that resolve as the child develops inhibitory pathways to the subcortical motor areas. Persistence of primitive reflexes indicates impaired brain development.

Reflex Description Age at resolution Functional significance
Stepping reflex
  • The infant is held upright and its feet are set onto the examining table → infant will place one foot in front of the other (stepping motion), with alternating flexion and extension of the legs.
  • Holding the infant in an upright position and lowering him/her to bring the feet in contact with the examining table → stepping motion
  • 2 months
  • Term infant: heel-to-toe stepping pattern
  • Pre-term infant: tip-toe stepping pattern
Asymmetrical tonic neck reflex (ATNR)
  • The infant's head is turned to one side → extension of the infant's ipsilateral arm and leg, with flexion of the contralateral arm and leg (fencing posture)
  • 3–4 months
  • ATNR aids in development of hand-eye coordination
  • Persistent ATNR has been linked to ADHD
Plantar grasp
  • 3 months
Palmar grasp
  • The infant's palm is stroked horizontally → closure of its palm
  • 3–6 months
Moro reflex (startle reflex)
  • 3–6 months
Reflexes which assist in feeding
  • 4 months
  • The reappearance of these signs in an adult is a sign of central neurodegenerative/vascular disease, often affecting the frontal lobes (frontal release signs)
Galant reflex
  • 4–6 months
Glabellar tap sign
  • The root of the nose (glabella) is tapped → blinking with each tap
  • 4–6 months
  • Persistence or reappearance is a frontal release sign
Babinski sign
  • The lateral border of the sole of the foot is stroked from heel to toe → dorsiflexion of the foot, fanning of the toes, and extension of the great toe
  • 12 months


Early developmental milestones

Gross motor milestones Fine motor milestones Cognitive milestones Social milestones Language milestones Self-care milestones
2nd month
  • N/A
  • Eyes follow objects past midline
  • Social smile
  • Recognizes mother's voice
  • Coos
  • N/A
4th month
  • Rolls over from front to back
  • Props himself/herself up on wrists in prone position
  • Head does not lag when pulled into sitting position
  • Shakes rattle when placed in palm
  • Reaches for objects persistently
  • Smiles at pleasurable sounds/sights
  • Localizes sound (turns head toward sound)
  • Laughs out loud
  • N/A
5th month
  • Sits with a curved back with arms supporting the trunk (parachute position)
  • Intentionally grabs objects (e.g., cube)
  • N/A
  • Recognizes primary care giver on seeing them
  • May start responding to his/her name
  • Squeals
  • Expresses anger (without crying)
  • N/A
6th month
  • Sits without support
  • Rolls over from back to front
  • Transfers objects from one hand to another
  • N/A
  • Regards self in mirror and vocalizes
  • Differentiates familiar and unfamiliar faces
  • Babbles
  • Starts speaking in monosyllables (“ma,” “ba,” “ah”)
  • Attempts to feed self
8th month
  • Commando crawls
  • Scissor grasp
  • Looks for dropped objects
  • N/A
  • Responds to his/her name
  • Responds to simple commands
  • Holds own bottle
  • Feeds self small foods (e.g., cereal)
9th month
  • Pulls himself/herself up to stand
  • Begins to crawl
  • Pincer grasp
  • N/A
  • Stranger anxiety may start
  • Separation anxiety may start
  • Waves goodbye
  • Speaks in bisyllables
  • Says mama and dada; but non-specific
  • N/A
10th month
  • Crawls well
  • Cruises (walks while holding on to objects for support)
  • N/A
  • N/A
  • Enjoys peek-a-boo
  • Says mama, dada specifically
  • Can sip from a cup held for him or her
12th month
  • Walks with support (holding hands)
  • Puts block in a cup
  • Imitates others
  • Gives/shares objects with others
  • Follows one-step commands with gesture (e.g., hands up)

  • Knows 1–3 words
  • N/A
15 months
  • Walks backwards
  • Builds stack of 2 blocks
  • Scribbles
  • N/A
  • Helps in house-work
  • Follows commands
  • Knows 3–6 words
  • Uses a spoon to feed him- or herself
18 months
  • Runs
  • Builds stack of 4 blocks
  • Kicks ball
  • N/A
  • Knows 6 words
  • N/A
2 years
  • Walks up and down stairs
  • Kicks a ball
  • Builds stack of 6 blocks
  • Copies a line
  • N/A
  • Exhibits selfish behavior; says “No, mine!”
  • Comforts others (empathy)
  • Speaks in 2-word sentences
  • Knows some parts of the body (e.g., eye, nose, mouth)
  • N/A
3 years
  • Pedals a tricycle
  • Builds stack of 8 blocks
  • Copies a circle
  • Understands gender difference
  • Toilet trained
  • Separates easily from parents
  • Initiates interaction with other children
  • Role plays “house”, “doctor”, etc.
  • Speaks in 3-word sentences
  • Mostly intelligible speech
  • N/A
4 years
  • Hops on one foot
  • Copies a square
  • May have imaginary friends
  • Play cooperatively
  • Tells complex stories
  • Names colors
  • Dresses oneself
5 years
  • Skips
  • Catches a ball
  • Doing a somersault
  • Copies a triangle
  • Can lace up shoes
  • Understands opposites
  • N/A
  • Can count
  • Intelligible speech
  • N/A


Normal growth in infants and young children

Growth charts are used to calculate a child's growth percentile by plotting the child's weight and height on standardized graphs.

  • Normal weight-for-age velocity
    • Term neonates lose up to 7% of their birth weight in the first few days after delivery and normally regain it within 2 weeks.
    • Birth weight should double by 4 months, triple by 1 year and quadruple by 2 years of age.
  • Normal height-for-age velocity
    • An infant's height increases by approx. 30% within the first 6 months and by approx. 50% within the first year.
    • Midparental height (target height):
      • height = [mother's height in cm + (father's height in cm - 13)]/2
      • height = [father's height in cm + (mother's height in cm + 13)]/2
  • Weight-for-height
    • Useful in detecting malnutrition in children < 5 years of age
    • Height at 1 year of age should be ∼ 50% more than the birth height.
  • Head circumference-for-age: used for microcephaly and macrocephaly screening, especially during the first 3 years of life

According to the Rule of Fives, normal growth rates in children can be approximated by multiples of five: birth–1 year (50–75 cm, 25 cm/year), 1–4 years (75–100 cm, 10 cm/year), 4–8 years (100–125 cm, 5 cm/year), 8–12 years (125–150 cm, 5 cm/year).


Infant nutrition and weaning


Formula feeds

  • Supplementation with formula only recommended if
    • > 7% loss of birth weight occurs in the first 10 days
    • Neonatal urine output is decreased
    • Neonatal stool output is decreased (< 3 small stools per day)
    • Maternal breast milk production is inadequate
    • Breastfeeding is contraindicated
  • Any lactose protein-based formula fortified with iron is recommended



  • Solid foods should be slowly initiated in infants between 4–6 months of age, with continued breast/formula feeding
  • The recommended initial weaning food is rice cereal fortified with iron
  • Honey should not be given to infants because of the risk of botulism.


Failure to thrive


  • Inadequate growth of a child for his/her age
  • Seen in up to 10% of children in the United States (most < 18 months of age)


  • Nonorganic FTT: no underlying disorder (∼ 90% of cases)
  • Organic FTT: due to an underlying disorder (∼ 10% of cases)
    • Inadequate intake of calories
    • Inadequate absorption of calories
    • Excessive loss of calories

Clinical features

  • Red flag features of organic FTT
  • Anthropometric criteria of FTT
    • Weight-for-age: < 5th percentile
    • Length-for-age: < 5th percentile
    • Body mass index-for-age: < 5th percentile
    • Deceleration of weight velocity that crosses 2 major lines on the growth chart



  • Treatment of underlying cause
  • Counseling parents on appropriate child nutrition
  • Formula supplementation for infants and calorie-dense food supplementation for toddlers
  • Close follow-up and monitoring of the child's growth


Well-child examination


Global developmental delay


Hearing impairment