According to the Centers for Disease Control and Prevention, the average height of a six-year-old boy in the U.S. is 45.5 inches. For girls the average is 45.3 inches. Average refers to the 50th percentile on CDC growth charts for boys and girls ages two to 20 years.
The economic conditions that are present when a child is in the early years of development may have a direct impact on his growth rate. Economic considerations can directly affect a child's access to things like health care, proper nutrition and clean drinking water. According to a Foxnews.com article titled "America No Longer Tallest Country in the World," height is correlated with numerous measures of a population's well-being.
While 85 percent of infants that are born prematurely in the U.S. will catch up to there peers before age two, in 15 percent of these cases other factors, including poor health, stunted intrauterine growth and health complications can continue to affect a child's growth rate through the developmental stages. According to Dr. Raye-Ann deRegnier, neonatologist at Children's Hospital of St. Paul and director of the NICU Follow-up Clinic, statistics about long-term growth in premature infants vary widely. Between six and 28 percent of premature infants may continue to display signs of stunted growth between the ages of eight to 18.
According to Foxnews.com, between 40 and 70 percent of growth may be related to genetics. On the other hand, the Magic Foundation for Children's Growth, which provides support and encouragement for families who have children who are experiencing growth-related difficulties, many growth hormonal deficiencies can be passed down from parent to child. These deficiencies are inherited and may be treatable.