Constitutional growth delay is a normal variation in the timing of physical development where a child grows and matures more slowly than peers but eventually catches up. It is the most common cause of short stature in children, alongside familial short stature. The child’s internal biological clock is simply running behind schedule, with all tissues, including bones, developing at a slower pace. This means puberty starts later, the growth spurt comes later, but growth continues longer than it does for other kids.
How Constitutional Growth Delay Works
In a typical child, bone maturity and chronological age move roughly in step. In a child with constitutional growth delay, the skeleton matures more slowly than the calendar would suggest. An X-ray of the hand and wrist can reveal this gap: a 12-year-old boy might have the bone development of a 9- or 10-year-old. This delayed bone age is the hallmark of the condition.
The delay isn’t limited to bones. All tissues develop on a slower timeline, which is actually reassuring. Because the whole system is shifted later, the child still follows a normal growth pattern. It just starts and finishes later than expected. A child with constitutional growth delay typically stays on or near the lower growth curves through childhood, then falls further behind peers around the age when puberty would normally begin. Once puberty does kick in, growth accelerates and the child moves back toward their genetic potential.
The exact biological mechanism isn’t fully understood, though researchers have identified a gene called LIN28B that appears to play a role in the timing of this delay.
The Role of Family History
Constitutional growth delay runs strongly in families. Between 60% and 90% of children with this pattern have a family member, on either side of the family, who was also a “late bloomer.” A parent who hit puberty later than classmates, grew several inches after high school, or was always the shortest kid in their class until a late growth spurt is a common story in these families. The trait is inherited through multiple genes from both parents, making family history one of the most useful clues during evaluation.
What It Looks Like at Different Ages
During early childhood, a child with constitutional growth delay may be slightly shorter than average but still growing at a normal rate. The real concern usually surfaces around ages 11 to 14, when classmates begin puberty and the child with constitutional delay does not. Boys with this condition enter puberty an average of 3 years later than their peers. For girls, the delay averages about 2.5 years. So while most boys begin developing around age 11 or 12, a boy with constitutional delay might not show the first signs until 14 or 15.
This gap becomes socially visible in middle school and early high school. Classmates grow taller, develop deeper voices, and change physically while the child with constitutional delay still looks younger. The height difference can be dramatic during these years, even though it’s temporary.
How Doctors Diagnose It
The single most important diagnostic tool is a bone age X-ray, typically taken of the left hand and wrist. Doctors compare the X-ray against a standardized atlas of images showing what bones should look like at each age. In constitutional growth delay, bone age lags behind chronological age by at least two standard deviations. A child who is 13 might have bones that look like those of a 10- or 11-year-old.
Growth velocity, the rate of height gain per year, is another key measurement. For children between ages 2 and 4, healthy growth is at least 5.5 centimeters (about 2.2 inches) per year. Between ages 4 and 6, the threshold drops to about 5 centimeters per year. From age 6 to puberty, boys should gain at least 4 centimeters per year and girls at least 4.5 centimeters. A child who is short but growing at a normal rate very rarely has an underlying medical problem; only about 2% of such children turn out to have true growth failure.
This distinction matters because it separates constitutional delay from conditions like growth hormone deficiency or thyroid disorders, where the growth rate itself slows down. In constitutional delay, the child is short for their age but growing at a steady, appropriate pace. Blood tests and other evaluations help rule out medical causes, but the combination of delayed bone age, normal growth velocity, and a family history of late development is the classic picture.
How It Differs From Familial Short Stature
These two conditions often get confused because both cause a child to be shorter than average. In familial short stature, the child has short parents and is genetically programmed to be a shorter adult. Their bone age matches their chronological age, and puberty arrives on a normal schedule. They simply reach a shorter adult height because that’s their genetic target.
In constitutional growth delay, bone age is behind, puberty is late, and the child has the potential to reach a normal adult height because they keep growing for longer. Some children have both patterns at once, which can make height prediction more complicated.
The Emotional Side
Even though constitutional growth delay is medically benign, the psychological effects on adolescents can be significant. Research has linked late pubertal timing to lower self-esteem, increased risk for depression, and social difficulties with peers. Teens with delayed development may withdraw socially, feel dissatisfied with their physical appearance, or develop unhealthy coping mechanisms. Some studies have found higher rates of disruptive behavior and even increased risk of substance use.
That said, the picture isn’t universally bleak. In one randomized trial, boys with constitutional delay were described as cooperative and not severely emotionally distressed compared to peers, even though they reported dissatisfaction with how their bodies looked. The emotional impact varies widely from child to child, and much depends on the support around them.
Treatment Options
Most children with constitutional growth delay don’t need medical treatment. The condition resolves on its own once puberty begins. For boys who show no signs of pubertal development by age 13 or 14, and whose bone maturity hasn’t progressed beyond what’s typical for an 11- or 12-year-old, doctors sometimes offer a short course of low-dose testosterone to jumpstart the process. This typically lasts 4 to 6 months, with one injection per month.
The goal isn’t to replace the body’s hormone production permanently. It’s to give the system a nudge. After the course ends, doctors check hormone levels to see if the body has started producing testosterone on its own, which would confirm the delay was temporary rather than a sign of a permanent deficiency. If levels haven’t risen, a second course can be tried. These low doses are carefully calibrated so they don’t compromise the child’s potential adult height by causing bones to mature too quickly.
For girls, a similar approach using low-dose estrogen is sometimes considered, though the decision-making process is less standardized and constitutional delay is diagnosed less frequently in girls.
What to Expect for Adult Height
The traditional reassurance is that children with constitutional growth delay will “catch up” and reach their full genetic height potential. The reality is slightly more nuanced. Many do reach a normal adult height, but research suggests some fall a bit short of their predicted target.
In one study of boys with constitutional delay, the average final height was 165.7 centimeters (about 5 feet 5 inches), compared to a predicted adult height of 170.7 centimeters and a target height based on parental stature of 171.8 centimeters. About a third of patients ended up more than 5 centimeters shorter than their predicted height. Other studies have found similar trends, with final heights typically reaching close to but slightly below genetic potential.
Not all children follow this pattern, though. Research by Wehkalampi and colleagues found that boys whose height percentile had dropped steadily between ages 3 and 9 were less likely to reach their full genetic height. Boys who maintained a stable percentile through early childhood and only fell behind at puberty had better odds of reaching their target. In a study by Salerno, boys with constitutional delay reached an average adult height of 166.4 centimeters, which closely matched both their target and predicted heights. The bottom line: most children with constitutional delay end up within a normal adult height range, though they may land a centimeter or two below what their parents’ heights would predict.