Growth and Development

Growth and development are vital signs of childhood, and monitoring them is an essential component of well child care. Early detection of problems provides an opportunity for intervention. This section addresses fetal, infant, childhood, and pubertal growth as well as developmental milestones and screening. More information on these topics can be found in the Pediatric Endocrinology rotation guide.

Growth

Growth is dependent on multiple systems and factors. Genetic growth potential plays a large role in determining ultimate adult height, but the interplay of hormones (growth hormone, insulin, thyroid, and sex hormones) and nutrition also strongly influences growth. Typical growth can be classified into four stages: fetal, infant, childhood, and pubertal. Atypical growth may herald many different problems, and the stage of the atypical pattern can help identify underlying issues.

Monitoring Growth: Growth Charts and Anthropometrics

Although norms for growth and formulas for calculating expected growth exist, the most common method for following growth is by plotting parameters on a growth chart. The most common parameters are weight, height (or length if the child is measured supine), and head circumference. Body mass index and weight-for-length charts can also be helpful. Other parameters used to measure growth in special circumstances include:

• waist circumference for obesity

• arm span as a proxy for height for a person who uses a wheelchair for mobility

• torso length for lung-function norms

• mid-upper arm circumference (MUAC) for malnutrition, especially in resource-limited settings

Many different growth charts are available. Growth charts for typical development are available from the World Health Organization (WHO; based on an international sample) and the Centers for Disease Control and Prevention (CDC; based on a domestic sample). The WHO growth charts are recommended for children in the United States through age 2 years, and the CDC growth charts are recommended for children age 2 years and older. Growth charts are also available for children with specific special health care needs (e.g., prematurity, trisomy 21 syndrome, Turner syndrome, achondroplasia, and Klinefelter syndrome).

Fetal Growth

Fetal growth is influenced by maternal nutrition, uterine size (restriction), and hormones (including insulin and insulin-like growth factors). Factors that impact fetal growth can have long-lasting effects throughout postnatal development and into adulthood. Growth charts to evaluate fetal growth at delivery based on gestational age can help determine whether a newborn is small, as expected, or large for gestational age.

Small for gestational age (SGA): SGA is often conflated with intrauterine growth restriction (IUGR). SGA refers to an infant whose birth weight is below the 10th percentile for the appropriate gestational age. IUGR describes a fetus that has not reached its growth potential. Symmetric SGA indicates that the growth parameters are proportionate. Asymmetric SGA refers to a weight that is disproportionately lower than length and head circumference. Asymmetric growth is an important clue to a concerning etiology for SGA.

Large for gestational age (LGA): LGA denotes an infant whose weight is greater than the 90th percentile for gestational age. LGA has implications for the birth process and immediate postdelivery care. Parental size is important to consider when evaluating the LGA infant. The most common pathology associated with LGA is intrauterine exposure to growth factors from gestational or pregestational diabetes or maternal obesity, which increase the risk of obesity in the infant. Infants with overgrowth syndromes (e.g., Beckwith-Wiedemann and Sotos syndromes) may also present as LGA.

Infant Growth

Infancy is a time of continued rapid growth. Immediately after birth, infants experience an expected weight loss. The rule of thumb is for infants to experience up to 10% weight loss within the first few days of birth that is regained (“back to birth weight”) by 2 weeks. Newt (newborn weight tool) is an online tool for comparing normal newborn weight loss to a large research sample; it is especially helpful for evaluating weight loss in an exclusively breastfed infant.

• After birth weight is regained, infants gain an average of 20-30 grams/day during the first 3 months.

• Growth then slows during the subsequent months. Infants typically double their birth weight by 6 months and triple it by one year. Although formulas and tricks exist to remember expected growth, after the first few weeks, it is easiest to follow growth on a growth chart.

• Linear growth (length) is also best tracked with the growth chart.

Childhood Growth

Most children have predictable growth and track along a growth curve. Sometimes a shift in percentiles can be normal; it warrants consideration but does not necessarily require immediate investigation with labs and imaging. A shift across two or more percentile lines is more likely to indicate an abnormality. Genetic height potential is also important to consider when assessing linear growth. Tall parents can expect to have taller children and short parents, shorter children.

Midparental height (the weighted average of the parental heights) is a predictor of adult height potential for a child but should be used with caution because it is not always accurate. Midparental height can be calculated using an online calculator or the following formulas:

• For boys: [father’s height (cm) + mother’s height (cm) + 13]/2 or [father’s height (in) + mother’s height (in) + 5]/2

• For girls: [father’s height (cm) - 13 + mother’s height (cm)]/2 or [father’s height (in) - 5 + mother’s height (in)]/2

Pubertal Growth

Pubertal growth is driven by sex hormones and accounts for about 17% of adult height. Linear growth decelerates at the onset of puberty just before it rapidly accelerates. A growth chart for height velocity (where the points plotted are the change in height rather than the height itself) can be helpful in evaluating normal growth in puberty. Pubertal changes are covered in more detail in the Puberty section of the Adolescent Care rotation guide.

Abnormal/Atypical Growth

Each parameter of growth can be too slow or too fast, and the etiology varies by age. The following are some of the most common causes of growth concerns:

Weight

Underweight/growth faltering: Growth faltering (also referred to as failure to thrive) is not a syndrome but rather a broad term referring to a physical sign that the body is not growing as expected. Historically, growth faltering was categorized as due to organic and inorganic causes, but this dichotomous view is considered outmoded. The etiology of growth faltering is often multifactorial. Although extensive laboratory screening is often not necessary, workup should follow a thorough history and physical exam and a pathophysiological approach to consider the causes of:

• inadequate nutrient intake

• inadequate nutrient absorption or increased losses

• increased nutrient requirements or ineffective utilization

• eating disorders: can occur at any age but are most common in adolescence (see Eating Disorders in the Adolescent Care rotation guide)

Overweight/obesity: With the growing obesity epidemic, overnutrition is the most common cause of excessive weight gain. Identifying an underlying disorder as the cause for excessive weight gain is much less common than with slow weight gain. However, maintain an index of suspicion for the following growth disorders:

• Juvenile acquired hypothyroidism: Children typically have constitutional symptoms, including decreased height velocity accompanying weight gain. Initial workup should include measures of free thyroxine (T4) and thyroid-stimulating hormone (TSH).

• Cushing syndrome: Cushing syndrome is more often caused by exogenous glucocorticoids than a pathologic endogenous source. Systemic symptoms often accompany weight gain. Growth failure (decreased height velocity) most often accompanies weight gain. A thorough history and physical should precede laboratory investigations.

Height/Length

Short stature: Primary linear growth problems often indicate a congenital, genetic, or endocrine abnormality and may provide clues to underlying systemic illness (e.g., celiac disease, inflammatory bowel disease, or a rheumatologic condition). A prepubertal child whose height velocity is <5 cm per year should be monitored closely. Worldwide, malnutrition remains a common cause of short stature. If no pathologic etiology is uncovered, familial short stature or constitutional growth delay may be the cause.

• Familial short stature (FSS) is idiopathic and considered a normal variant. With FSS, children have normal height velocity, normal bone age, and normal lab findings. They are expected to ultimately reach their calculated midparental height.

• Constitutional growth delay (CGD) occurs in children with normal size at birth and normal growth during early childhood but who experience a growth delay during early adolescence. Their bone age is closer to the age expected for their height than their chronologic age (i.e., skeletal age is younger than age in years). Children with CGD will experience catch-up growth and are expected to achieve an adult height consistent with their genetic potential.

Tall stature: Excess linear growth, or tall stature, is most often constitutional (familial and due to an expected genetic potential) or a result of overnutrition. Obesity can increase linear growth in childhood but does not increase adult height. Paradoxically, tall stature may decrease adult height due to early puberty, excess estrogens, and advanced bone age. Much less frequently there is a pathologic cause of tall stature. Pathologic causes include:

• hyperthyroidism

• precocious puberty

• growth hormone excess

• familial glucocorticoid deficiency

• chromosome duplication (e.g., Klinefelter syndrome or 47,XXY)

• genetic syndrome (e.g., Weaver, Marfan, or Sotos syndromes)

Head Circumference

Abnormalities of head growth are the most concerning and are more often associated with pathology because head circumference reflects brain growth or another intracranial process. Proper measurement and recording are important to confirm before proceeding with a workup. In infants especially, it is important to observe head shape and ensure that an inaccurate measurement does not result from a craniosynostosis.

Microcephaly: Microcephaly refers to a head size that is smaller than expected based on age and other growth parameters. It usually indicates that the brain is not growing properly. Possible causes include:

• congenital infections

• prenatal exposure to toxicants such as alcohol

• interruption of the blood supply to the baby’s brain, either during development prenatally or postnatally (e.g., a stroke)

• severe malnutrition either prenatally or in infancy

• genetic syndromes

Macrocephaly: Macrocephaly refers to a head size that is larger than expected for age (>98th percentile). Evaluation for macrocephaly should be initiated in a child with any of the following findings:

• a single occipitofrontal circumference (OFC) measurement is abnormal

• serial measurements reveal progressive enlargement

• OFC increase is >2 cm per month in infants younger than 6 months

Familial head size is important to consider when assessing macrocephaly. Parental head measurement is the gold standard for identifying large familial head size. Alternatively, inquiring about difficulty in finding hats that fit can serve as a proxy for parental head measurements. Macrocephaly raises concern for an intracranial pathology including:

• hydrocephalus: cerebral spinal fluid (CSF) retention leads to increased head circumference

• intracranial mass

• subdural fluid collection

• megalencephaly: increased brain mass that may be benign or a result of a syndrome or systemic disorder

• benign enlargement of the subarachnoid space seen on head ultrasound of normally developing infants; as the name implies, a nonpathologic cause of macrocephaly often seen in families with large heads

Development

As with growth, development is rapid in the first few years of life. Developmental milestones follow a predictable course. Early identification of developmental delays can facilitate referral to therapeutic services that can improve the trajectory of developmental attainment. Development is divided into the following domains:

• cognitive: reasoning, memory, and problem-solving skills

• language: receptive and expressive communication, speech, and nonverbal communication

• fine motor: movements using hands and small muscles

• gross motor: movements using large muscles

• social-emotional and behavioral: attachment, self-regulation, and interaction with others

Screening: In addition to developmental monitoring at every well child visit, the American Academy of Pediatrics (AAP) recommends the use of standardized, validated screening tools for assessing general development at ages 9, 18, and 24 or 30 months and an autism screen at ages 18 and 24 months. In collaboration with the CDC, they provides an online database of screening tools. Unfortunately, an estimated 40% of pediatricians do not consistently complete recommended screenings, making screening a ripe topic for practice quality improvement.

Developmental milestones: A review and links to developmental milestones in gross and fine motor skills, self-help, problem-solving, social and emotional, and receptive and expressive language domains from ages 2 months through 5 years can be found here. The milestones were created to represent ages at which ≥75% of children can be expected to exhibit the skills.

Concerns for developmental delays: Early assessment of developmental milestones to identify developmental concerns allows for early intervention. The appropriate resources depend on the specific concerns identified (see the CDC’s developmental milestones).

Early intervention (EI) services: Although EI services are provided by different local implementing agencies, every community has an EI program as mandated by federal law through the Individuals with Disabilities Education Act (IDEA). EI services are provided for children from birth to age 3 years. The EI program conducts an assessment and, if a child qualifies, provides physical, speech and language, and occupational therapies depending on need. In addition to clinician referral, parents can self-refer. Qualification depends on degree of delay or another qualifying condition such as trisomy 21, in utero substance exposure, prematurity, and many others.

Special education services: After 3 years of age, therapies and special education services are provided through the public school system. For children who do not “graduate” from EI before aging out, or for those whose developmental concerns are identified after age 3 years, the school will provide an assessment and create an Individualized Family Service Plan (IFSP) or Individual Education Plan (IEP) as appropriate. Children who do not attend public school because of age or who attend private school are still entitled to receive services through the public school system.

Developmental-behavioral pediatrician or child neurologist consultation: A specialist consultation may be warranted for children who have profound delays, unexplained delays, regression, or other concerns. Developmental pediatricians also see children for other concerns (e.g., behavioral problems, attention disorders, feeding and toileting problems, and learning disorders).