Every parent knows that feeling. As our kids grow, we anxiously check their progress against the development charts in childcare books, looking for signs that all is normal. Much of the time, we're reassured.
But surprisingly often, kids' abilities don't match the charts so neatly. Although children typically walk by 12 to 13 months, for instance, the "normal" boundaries can be considerably wider -- as early as 9 months and as late as 17. In fact, nearly 30 percent of children fall into these outer categories, estimates Kathryn Ellerbeck, M.D., a pediatrician at the Developmental Disabilities Center at the University of Kansas School of Medicine, in Kansas City. And 10 percent are "abnormally" late in reaching at least one milestone -- even though there may be nothing wrong.
Child development encompasses five major areas: gross motor skills (like crawling); fine motor skills (hand use); language; perceptual-cognitive development (the ability to learn colors and letters); and social-emotional development (playing with other children). But parents are most aware of crawling, walking, and talking, and it's late progress in those areas that triggers our worst fears.
Late development can indicate brain damage, neurological problems, or autism. But in most cases, there's no problem at all, or it's minor and easily corrected.
*Not their real names.
Carol Lynn Mithers is the author of Therapy Gone Mad.
What Creates a Delay?A wide array of factors can cause a child to lag for a time. Prematurity, for example, can cause lateness in several areas. Because the "gestational age" of a 9-month-old who was born two months early is only 7 months, she's not going to meet the milestones that her chronological age suggests, says Claire Lerner, a child-development specialist at Zero to Three, a Washington, D.C.-based nonprofit educational organization.
More typically, though, a child is late in one developmental area. Learning to walk requires intense physical effort, and "kids have different amounts of strength," says Ed Tronick, Ph.D., chief of the Child Development Unit at Children's Hospital, in Boston. "There are infants who have fabulous muscle tone -- they feel compact -- and others who are all over the place."
How much a child is encouraged to be physical can also affect when she begins to get around on her own. "One of the unfortunate side effects of advising parents to put their infants to sleep on their back to prevent sudden infant death syndrome is that some parents are reluctant to put babies on their belly even while they're awake," says Tronick. When on their tummies, babies naturally try to push up, which strengthens the upper body and prepares it for crawling.
Some kids develop differently from others because that's just how their bodies are programmed. "A child may never crawl, but go right into walking," says Dr. Ellerbeck. "For other late walkers, the parts of their brains that control movement are fine. They just work a little later."
Tight-Lipped TotsLike late crawling and walking, a delay in talking doesn't mean there's a problem. Heredity and your baby's temperament can make for a linguistic late bloomer, as can a parent's anticipating a child's every need rather than letting him speak for himself. Some kids simply don't have a feel for words, which is not to say they're not smart. To the contrary, says Alice Sterling Honig, Ph.D., professor emerita of child development at Syracuse University, in New York, "It's that these kids are more spatially than verbally oriented. I've known little ones who didn't read until second grade who grew up to become brilliant scientists." Albert Einstein, for one, did not begin to talk until the age of 3.
Being a twin can also cause speech delays. "Multiples sometimes communicate in their own private language," says Dr. Ellerbeck. "They understand what they're saying, but no one else can." The same often holds true for bilingual kids. "When a child is learning two languages simultaneously, he's taking in more information," says Honig. "Sometimes that means the learning goes more slowly."
When Lateness Is a ProblemIf a child is late reaching one milestone, check to see if other developments are on schedule. If speech is delayed, does the child make eye contact and interact with others? Does she regularly use gestures or noises to make her feelings known? If so, she is probably fine.
Still, experts caution that when a child is late in developing, a parent shouldn't simply assume that all is well. Talk to your pediatrician to rule out any problems, says Dr. Ellerbeck, since they may need early treatment. "Children with weak muscle tone may become uncoordinated and fall a lot," she says. "Early intervention can help them move more normally."
"Kids who understand language but can't find the right words to express their thoughts are at risk of reading problems," says Julian Haber, M.D., a developmental pediatrician at the Child Study Center, in Fort Worth, Texas. "Language delays should be addressed before a child starts school."
Kimberly Michaels had her son evaluated by a neurologist, who found nothing wrong. Joshua had low muscle tone, and it would just take him a little longer to develop the strength to crawl and walk. Now, at age 4, "he's running and playing with abandon," says Michaels. "He just needed some extra time."