They lack enough of a key hormone that urges their bodies to grow.
In the past, the condition could condemn them to a life of stunted growth and compromised health.
Now, doctors are replacing the missing growth hormone and giving these children a chance at a normal life, along with extra inches of height. The hormone treatment, which involves several years of injections, received federal government approval late last year.
"We're trying to get the word out to parents and physicians so they will be aware that this treatment is available and we can help these children," says Dr. Pinchas Cohen, a pediatric endocrinologist at the University of California at Los Angeles.
Cohen is one of several doctors around the country who are using the growth hormone treatment on children who are considered "small for gestational age" -- severely underweight at birth -- and don't grow to a normal weight and height during the first two years of life. The children are nearly dwarfs, he says.
About one in 40 children is born much smaller than average -- generally, less than 5 pounds after a full-term pregnancy. About 10 percent of those children don't catch up to their peers later in life.
They grow up to be very short adults, typically below 5-foot-3 for men and 4-foot-11 for women, Cohen says. They also suffer from medical problems, including obesity, diabetes and high blood pressure.
Not every small adult has the "small for gestational age" disorder. Some small people have plenty of growth hormone but are simply genetically programmed to be shorter than most other people.
However, other children completely lack growth hormone. For decades, doctors have routinely treated them with growth hormone. Often, they must continue treatment into adulthood because lack of the hormone can cause medical problems, Cohen says.
Not until last year, however, did the federal government approve the use of growth hormones to treat children who were small for gestational age but weren't missing all their growth hormone. Treatment usually begins at age 2 and lasts for two years or longer, Cohen says.
"We know that their growth improves dramatically," he says. "Their final height will be increased by anywhere from 4 to 8 inches. That's pretty substantial. The psychological benefits might be seen even sooner by making the children comparable to their peers within a few years."
However, Cohen says it's not clear if the hormone treatment will help the children avoid the variety of medical problems they are prone to developing.
Side effects of the treatment are extremely rare, he says, occurring less than once in every thousand cases.
"It's the same hormone that our bodies make anyway. These children seem to have an insufficient amount of it, so we're giving them a little bit extra of a natural hormone," he says.
While the treatment isn't cheap -- it costs between $2,000 and $10,000 a year -- Cohen says it lets children avoid the psychological and physical challenges of being much smaller than their peers. Medical insurance often covers the costs, he says.
It's possible to use growth hormone to treat children who are short but don't suffer from being "small for gestational age." But Cohen and many other endocrinologists advise against that.
"The problem is nobody knows how safe that is, and nobody really likes to do that just for the sake of an inch or two," says Dr. John Seibel, an endocrinologist and former past president of the American Association of Clinical Endocrinologists.