• 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
  • The infant's foot is stroked from the toe to the heel → plantar flexion (curling in) of the infant's toes
  • 3 months
Palmar grasp
  • The infant's palm is stroked horizontally → closure of it's palm
  • 3–6 months
Moro reflex (startle reflex)
  • The infant is held in the supine position and the head is supported by the examiner's hand. The infant's head is then suddenly allowed to fall back → abduction and extension of the arms, opening of the hands, followed by adduction of the arms and flexion of the elbows
  • 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
  • The infant is held in the prone position and paravertebral region is stroked on one side → rotation of the ipsilateral hip of the infant
  • 4–6 months
Glabellar tap sign
  • The root of the nose (glabella) is tapped → blinking with each tap
  • 4–6 months
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
Landau reflex
  • The infant is placed in the prone position → arching of the back and raising of the head
  • 24 months
  • Diminished in infants with hypotonia (floppy infant syndrome)


Early developmental milestones

Gross motor milestones Fine motor milestones Cognitive milestones Social milestones Language milestones Self-care milestones
2nd month
  • Raises chest and shoulders (in prone position)
  • 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”)
  • Obeys “No!”
  • Speaks to self in mirror
  • 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 charting

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

  • Normal weight-for-age velocity
    • Term neonates lose up to 10% of their birth weight in the first few days after delivery; birth weight is normally regained within 2 weeks
    • Birth weight should double by 4 months of age and triple by one year of age
  • Normal height-for-age velocity
    • From birth to 6 months: 2.5 cm (1 in) per month
    • From 6 months to 1 year: 1.3 cm (0.5 in) per month
    • Height at 1 year of age should be ∼ 50% more than the birth height
  • Weight-for-height: useful in detecting malnutrition in children < 5 years of age
  • Head circumference-for-age
  • Tooth eruption
    • The 2 lower central incisors are the first to erupt, at 5–9 months of age
    • All 20 temporary/deciduous teeth should normally have erupted by 2.5 years of age
    • Delayed tooth eruption can be physiological (hereditary) or a sign of underlying disease (e.g., rickets, hypothyroidism, hypopituitarism, Down syndrome)
    • Permanent teeth start to replace temporary teeth at ∼ 5 years of age


Infant nutrition and weaning


  • Exclusive breast feeding is recommended until the infant is 6 months of age
  • On-demand feeds are recommended
  • Advantages of breastfeeding

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
  • One new food should be introduced per week to allow easy identification of food allergies.
  • Pureed meat, green leafy vegetables, dried beans are good sources of iron and zinc.
  • Honey should not be given to infants because of the risk of botulism.
  • Cow's milk can be introduced into the diet after 1 year of age.


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
    • Developmental delay
    • History of recurrent vomiting and diarrhea
    • History of recurrent infections
    • Failure to gain weight despite adequate feeds
    • Abnormal physical examination (e.g., lymphadenopathy, edema, cardiac murmur, organomegaly)
  • 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


  • History of feeding habits (e.g., quantity of feeds, frequency of feeds, food refusal)
  • Laboratory studies
    • Complete blood count and ESR: to evaluate for anemia, chronic infection, and leukemias/lymphomas
    • Urinalysis: to evaluate for chronic urinary tract infection, signs of renal disease, or inborn error of metabolism
    • Liver and renal function tests: to evaluate for underlying hepatic/renal disease and electrolyte imbalance due to chronic vomiting and diarrhea
    • Thyroid function tests
    • Tests for HIV; , tuberculosis, and immunoglobulin levels
  • Imaging


  • 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

Indicators of possible developmental delay
2 months
  • No response to loud sounds
  • Does not watch things as they move
  • No social smile
  • Doesn't bring hands to mouth
  • Absence of even brief neck control
4 months
  • Absence of the above milestones and
  • Does not coo or make sounds
6 months
  • Absence of the above milestones and
  • Does not reach out for objects
  • Shows no emotional bonding with primary care giver
  • Does not babble or speak in monosyllables
  • Does not laugh
  • Is either hypo/hypertonic
9 months
  • Absence of the above milestones and
  • Does not sit even with support
  • Does not pull to stand
  • Does not speak in bisyllables
  • Cannot differentiate familiar people and strangers
  • Does not transfer objects from hand-to-hand
12 months
  • Absence of the above milestones and
  • Does not crawl
  • Does not stand with support
  • Does not point to objects
  • Regression of achieved milestones
18 months
  • Absence of the above milestones and
  • Does not walk
  • Does not know at least 6 words
  • Does not have separation anxiety
2 years
  • Absence of the above milestones and
  • Does not know how to use a spoon or brush teeth
  • Does not mimic others
  • Does not follow simple instructions
3 years
  • Absence of the above milestones and
  • Has frequent falls
  • Cannot climb up/down stairs
  • Does not make eye contact
  • Does not role play
  • Does not interact with other children
4 years
  • Absence of the above milestones and
  • Cannot jump
  • Cannot scribble
  • Resists dressing, using the toilet
5 years
  • Absence of the above milestones and
  • Shows extreme behavior (aggressiveness, excessive shyness/fearfulness)
  • Easily distracted
  • Cannot distinguish between real and make believe
  • Does not draw pictures
  • Does not know one's own name
  • Diagnostics
  • Treatment
    • Treatment of the underlying cause (when reversible)
    • Early intervention to minimize the severity of disability
    • Multidisciplinary team: neurologists, orthopedics, physical therapists, speech therapist, nutrition
    • Special schooling and occupational therapy


Hearing impairment