Human Growth and Development

Issues of Concern

Measurement of Growth

Anthropometry is the gold standard by which clinicians can assess nutritional status. The major anthropometric measurements for ages up to 2 years are weight, length, weight for length, and head circumference. The major measurements for children above 2 years are weight, height, body mass index (BMI), and head circumference for the 2-3 years age group. 

1. Length or height: For children less than 2 years or children with severe cerebral palsy, the length is the ideal way of measuring stature. Length is measured by placing the child supine on an infant measuring board. For children aged more than 2 years, standing height is measured in the stadiometer after removing shoes. The supine length is usually 1 cm higher than the standing height. Length and height can be documented to the closest 0.1 cm. For children with severe cerebral palsy or spinal deformities, upper arm length, tibial length, and knee height can be useful to assess stature.[12]
2. Weight: Kids below 1 year are weighed on a scale after removing their clothes, shoes, and diapers and documented to the closest 0.01 kg. The kids outside infancy should be measured without shoes, with little or no outer clothing, and documented to the closest 0.1 kg. 
3. Head circumference or occipitofrontal circumference: Head circumference is assessed by measuring the largest area from the prominent site at the back (occiput) to the frontal prominence above the supraorbital ridge. Brain growth is maximum in the first 3 years of life, so head circumference is used in children under 3 years.  It is measured as the maximum diameter through the supraorbital ridge to the occiput and documented to the closest 0.01 cm. Microcephaly is more than 2 standard deviations below the mean. Macrocephaly is more than 2 standard deviations above the mean. 
4. The measure of adiposity:
   1. Body mass index (BMI) is a useful predictor of adiposity. BMI is calculated using weight (kg) / height (m)². BMI is the single best indicator for detecting overweight or obesity.
      • < 5th percentile - underweight 
      • 5th to 84th percentile - normal 
      • 85th to 95th percentile - overweight 
      • 95th to 98th percentile - obesity 
      • More than 99th percentile - severe obesity
   2. The weight-to-length ratio is an alternative for body mass index in predicting adiposity in less than 2 years. 
   3. Self-assessment of the hip-to-waist ratio can help to guide the measure of central adiposity,
   4. Triceps and subscapular skinfolds can also be a useful measure of adiposity.[13]
5. Body proportions
   1. The upper segment to lower segment (U/L) ratio is 1.7 at birth, 1.3 at 3 years, and reaches 1.0 at greater than 7 years. A higher U/L ratio is a feature of short-limb dwarfism.
   2. The arm span-to-height ratio is a fixed ratio across all ages. The ratio of more than 1.05:1 is suggestive of Marfan syndrome.[14]
6. Sexual maturity: Tanner stage can be used to assess sexual maturity.
7. Skeletal maturity: Bone age can be determined by doing Hand & Wrist radiographs from 3 to 18 years of age. 
8. Dental assessment: Primary tooth eruption begins with the central incisors at 6 months. No single tooth by 13 months of age is of concern. Permanent tooth eruption starts at 6 years of age and continues up to 18 years of age. 

Growth Velocity 

The growth velocity is different at different stages of life. Also, different tissues grow at different rates at the same stage of life. The lymphoid tissues can exceed adult size at 6 years of age. Girls are taller than boys at 12 to 14 years, but later, they do not grow taller than their male counterparts. Growth velocity is maximum during infancy and adolescence. The head circumference reaches closer to adult size by 6 years of age. The prepubertal height velocity of less than 4 cm per year is of concern. During puberty, the height velocity is 10 to 12 cm per year in boys and 8 to 10 cm per year in girls. The prepubertal weight velocity of less than 1 kg per year is of concern. Weight velocity is highest during puberty, up to 8 kg per year.

Stages of Development

Development is a continuous process from neonatal to adulthood. Though growth ceases after adolescence, adolescence is not the end of development. Each developmental stage has a new set of challenges and opportunities. 

1. Infancy: Development progress in the cephalo-caudal direction and from the midline to the lateral direction.  A 3 to 4-month variation can be used to achieve the developmental milestone. Social development is a cortical function that develops earlier than motor skills. The lack of a social smile for 4 weeks is of concern. At birth, the infant is equipped with primitive reflexes. Certain primitive reflexes help in the normal physiology of infants. Sucking and rooting reflexes help inefficient feeding. Most of the primitive reflex disappears to facilitate the mature development process. For example, the grasp reflex disappears by 6 months, and the child develops mature grasp development from 6-12 months.
2. Early and late childhood: Between ages 1 and 3, locomotion and language are crucial. The best predictor of cognitive function is language. Fine motor skills are related to self-help skills. The most common development in early childhood is to establish self-identity. A child may have an independent existence by 3 years of age. The kids learn independent existence skills like feeding behavior, toilet training, and self-dressing during this stage of early and late childhood. Questioning skills develop during early childhood development.   
3. Adolescence: Adolescence is hallmarked by puberty changes, which occur 2 years earlier in females than males. Puberty changes are assessed using the Tanner staging. Acceptance of a new body, separation from home, and establishing oneself as an independent adult are significant challenges in puberty.

Psychosocial Development 

Erikson has postulated 8 stages of psychosocial development.

1. Trust and mistrust in infancy (< 1 year): Infants develop trust with a warm response from the caretaker.  
2. Autonomy and doubt in the toddler age group ( 1 to 3 years):  Children feel autonomous if caregivers encourage independence. Otherwise, they doubt their abilities.
3. Initiative and guilt in the preschool age group (3 to 6 years): Kids experiment with their ambitions through imaginative play. If parents do not encourage their initiative, the kids feel guilt.  
4. Industry and inferiority in early school years: Children learn to work as a group in school. They have feelings of inferiority if their peer environment is hostile.
5. Identity and role confusion in adolescence: Self-identity is a significant development. 
6. Intimacy and isolation in early adulthood: Those who cannot establish relationships or intimacy are prone to be socially isolated.
7. Generativity and stagnation in middle adulthood: Parenting is the best example to guide the younger generation. 
8. Ego integrity and despair in late adulthood: People who are unsatisfied with what they did during their lifetime are in despair.

Clinical Significance

Understanding normal growth and development milestones is important for a clinician evaluating pediatric patients. It isn't easy to recognize aberrance if you are unfamiliar with normal. By using growth charts and doing the developmental screening, challenges in care can often be identified early.

Growth Charts

• The CDC charts include children raised in various nutritional conditions in the United States. The CDC charts' normal range is between the 5th and 95th percentiles. 
• The WHO growth chart describes children raised under optimal environmental conditions from birth to 5 years. The normal range is expressed as a Z score between -2.0 and +2.0, corresponding to 2 and 98 percentiles. Z-scores are the number of Standard deviations from the mean.
• The WHO growth charts represent a growth standard, whereas the CDC growth chart represents a growth reference. WHO growth charts are used for children under 2 years of age, and the CDC growth charts are used in children for more than 2 years. 
• When using the WHO charts, the prevalence of short stature and obesity is similar to the CDC charts, but the underweight prevalence was lower than the CDC charts.[15][16]
• Preterm infants 
1. During the neonatal intensive care unit stay, preterm growth charts like Fenton growth charts are used for all preterm infants under 37 weeks of gestational age. Fenton charts can be used from 22 weeks of gestational age and up to 10 weeks post-term.
2. WHO charts are useful to monitor the growth of preterm infants less than 37 weeks after discharge. The corrected postnatal age is used for up to 2 years. The corrected age for preterm kids is calculated as the actual age in weeks - (40 weeks - gestational age at birth in weeks).[17]

Developmental Screening 

Only 20% of the children with developmental delay in the United States receive early intervention before 3 years. Early intervention is useful in high-risk children to improve their cognitive and academic performance. Less than 50 % of clinicians only use standardized screening tools in practice. Time constraints and lack of training are essential barriers to using the developmental screening tool. Standard screening tools include the Ages and Stages Questionnaire (ASQ), the Parents' Evaluation of Developmental Status, and the Child Development Inventory. ASQ tool can be used for up to 66 months. The PEDS tool can be used up to 8 years of age.  Gross and fine motor milestones are assessed at every well-child visit in the first 4 years. Standardized developmental assessments using ASQ are mandatory at 9, 18, 24, or 30 months.[18] The clinician may screen more frequently if there are risk factors like prematurity, lead exposure, or low birth weight. Autism screening needs to be done at 18 and 24 months of age. If the screening tool reveals developmental delay, the child needs referrals to developmental pediatricians. Children up to 3 years with developmental delay are referred to early intervention programs, and children above 3 years of age are referred to special education services. 

Red Flags in Growth and Development 

• Red flag signs in motor development are persistent fisting for more than 3 months, the persistence of primitive reflexes and rolling before 2 months, and hand dominance before 18 months. 
• No babbling by 12 months, no single words by 16 months, no 2-word sentences by 2 years, and loss of language skills are red flags.
• Children whose height or weight readings are below the 5th percentile, above the 95th percentile, or cross 2 major centile lines need further evaluation.

Enhancing Healthcare Team Outcomes

The interprofessional team should understand the developmental stages that their patients go through during early childhood. We should increase the awareness of healthcare professionals about the importance of standardized growth monitoring and the appropriate use of growth charts. Also, they need adequate training to use standard developmental screening tools. Every clinician managing pediatric patients should have appropriate awareness of referral services to early intervention for eligible patients. Interprofessional collaboration can improve patient outcomes as developmental delays require prompt intervention when caught; earlier is always better. Children up to 3 years with developmental delay are referred to early intervention programs, and children above 3 years of age are referred to special education services.