When Lily Vasey was an infant, her mother, Kate, assumed she'd hit all her milestones on time, just as her older son, William, had. But when Lily turned 6 months  -- the average age when babies begin to crawl  -- she showed no signs of doing so. Instead, she'd pull herself along the floor, as her mom describes, "like a soldier slogging through mud." "Her pediatrician told me she was okay, and as each month went by, I just figured she'd crawl the next one," says Vasey, of Rochester, New York. But Lily, now 3, never did. She dragged herself with her arms until she started walking at 14 months. "It was very surprising  -- I never expected that my daughter would skip such a big milestone," says Vasey.

Lily's story isn't even that unusual. According to experts, more kids seem to be hitting numerous motor (movement) development milestones later or skipping them altogether. The topic is increasingly becoming controversial in the medical community. While the conventional wisdom is that there's no harm in skipping the crawling stage, a growing number of experts  -- particularly pediatric occupational therapists  -- say that crawling is actually a critical developmental milestone whose long-term benefits we're only now beginning to recognize. We spoke to nearly 20 authorities on both sides of the issue to get the scoop on this heated debate.

A significant achievement

In 1994, several national health organizations, including the American Academy of Pediatrics, started encouraging parents to put babies to sleep on their backs to help prevent sudden infant death syndrome (SIDS). The lifesaving outcome: The incidence of SIDS has decreased more than 50 percent. But according to several studies, an inadvertent result of the campaign is that more kids are achieving motor milestones later, or bypassing them altogether, because their upper bodies aren't as strong due to lack of time spent on their stomachs. When babies skip crawling  -- and by this we mean the classic hands-and-knees crawl  -- then they miss out on more opportunities to develop that strength and wind up with weaker upper body muscles.

"Crawling helps strengthen the hands, wrists, elbows, and shoulders because babies have to constantly activate them to support their body weight," says Felice Sklamberg, a pediatric occupational therapist at New York University's School of Medicine. "We're seeing that because non-crawlers aren't as strong, they have a harder time as older children pulling themselves out of a pool, climbing a jungle gym, or even picking themselves up from the floor."

Skipping this milestone can also affect a child's ability to hold silverware or a pencil down the road, since the weight-bearing experience of crawling helps develop arches and stretch out ligaments in the wrist and hand that are needed for fine motor skills. "During the crawling period, the large joint at the base of the thumb is expanded into its full range of motion, so noncrawlers may have messier handwriting, for example," explains Mary Benbow, an occupational therapist and a leading expert on pediatric hand development.

Crawling is a unique experience in other ways as well. "It's a real step up for coordination because it's the first opportunity to practice bilateral coordination  -- using the arms and legs in reciprocal movements," says Jane Case-Smith, director of the division of occupational therapy at Ohio State University's School of Allied Medical Professions in Columbus and an early-intervention specialist. "This skill is used in activities like getting dressed, self-feeding, and sports. A child who sidesteps crawling may have more of a struggle catching up."

Babies who skip any kind of scooting or dragging miss out on the benefits of being on the floor as well. "Children learn through interaction with their hands. They don't get as much if they go straight to walking, because then they need to use their hands for balance," says Karen Hendricks-Muñoz, M.D., chief of neonatology and associate professor of pediatrics at New York University's School of Medicine. "Navigating on the ground also helps visual spatial skills and depth perception develop more quickly."

Dina Roth Port is a freelance writer and mother of two in Boca Raton, Florida.

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