For the first six months of his life, your baby has relied on you to set him in motion. You've carried him, bounced him, rocked him, propped him up with pillows, and danced with him on your lap. Now he's driven to move and groove on his own.
Two developments converge to help baby put one arm in front of the other and crawl. For one, your baby's sense of balance dramatically improves. Second, your baby's muscles have grown stronger from having had a repertoire of experiences in different positions. Here's a typical scenario: Your 7-month-old is sitting up on her own and reaches across her body to grab at a toy. The act of reaching causes her to lose her balance. In an attempt to right herself, she twists her body and thrusts her hands out in front of her, landing on her tummy. Once on the floor, she may raise her head and gather her knees under her as well as her hands. She's on the runway in crawling position!
Of course, "crawling" means different things to different babies. Another baby may, from a sitting position, discover that she can push her hands against the floor and scoot on her bottom to get from here to there.
Regardless of her personal style, her first attempts may not lead to any forward movement -- she may get up on all fours only to get stuck in neutral, or she may try pushing her palms on the floor and find herself moving backward instead of forward.
Indeed, it takes a while to get good at anything, and crawling is no exception. According to New York University psychologist Karen E. Adolph, PhD, who has conducted numerous studies on the topic, crawling speed increases by a staggering 720 percent over the first 20 weeks of learning, while the size of an infant's crawling "steps" increases by 265 percent. In other words, once she gets the hang of things, watch out: Crawlers can move!
Crawling doesn't merely boost physical skills. As your baby learns to move independently, she will become more aware of her surroundings and better able to navigate them, says Lise Eliot, PhD, assistant professor of neuroscience at the Chicago Medical School and author of What's Going On in There? How the Brain and Mind Develop in the First Five Years of Life (Bantam). There's a big difference between being carried around and getting somewhere yourself. Crawling helps kids learn to keep track of locations and use landmarks to orient themselves, e.g., she gets to her basket of toys by looping around the coffee table and heading toward the kitchen. "It's like the difference between driving the car and just riding along. Babies learn to solve problems by doing things for themselves. It's not calculus, but it's a definite cognitive advance," says Eliot.
Of course, just when she's learned to get to the coffee table for the remote, someone goes and leaves it on the chair! A shifting environment isn't the only learning curve baby has to negotiate. The very act of balancing in different positions takes place in the context of her own rapidly changing body. Her arms and legs might actually be longer from one month to the next, and she may weigh more. Further complicating the mix, as baby's skills become more advanced, her abilities change. In one of her studies, Adolph gathered a group of 9-month-olds who had been sitting up for a while but had only just started to crawl. In the first scenario, the babies were placed on a platform in view of a bright red ball 2 feet below. In their excited pursuit of the ball, the babies would have fallen off the platform if no one had caught them. Yet when they were seated with their legs dangling over the edge of the platform, the babies gazed at the tempting red ball but didn't reach for it because they knew they would fall.
Why were babies more cautious in the second instance? The 9-month-old babies, with several months' of sitting experience, knew what they could and couldn't do from that position. On the other hand, as novice crawlers they lacked both the depth perception and eye-hand coordination to judge their own abilities correctly during the precarious new activity.
In short, every new motor milestone for babies involves learning how to balance and move in a different way, requiring constant fine-tuning of their bodies and movements as they try new tasks.
Not all babies crawl before they learn to walk. In general, babies are achieving motor milestones at a later age than they did 15 or 20 years ago, in part because most of them are now put to sleep on their back. The Back to Sleep Campaign has significantly reduced the risk of SIDS, but the unintended fallout is that babies spend less time on their stomach. Experts recommend giving baby tummy time during the day so he has a chance to build upper-body strength and coordination.
Still, not all babies will tolerate being facedown on the floor; others are destined not to crawl no matter what. The good news is there is no evidence that babies suffer motor-skill delays if they don't crawl. The important thing isn't so much the crawling, says Robin Adair, MD, who directs the infant, toddler, and preschool clinics at the University of Massachusetts Memorial Health Care Center, in Worcester, "but giving your baby lots of chances to build up his muscles and experience the world from different views."
Ironically, just as a baby learns to crawl and can get away from you, he may also realize that he's terrified if you're out of his sight. He often brings this on himself by crawling into another room or rounding a corner. Of course, his hysteria at being separated from you (or any other trusted primary caregiver) can also be brought on when you leave, even if he's in the care of someone he knows. This phenomenon of being so attached to one person that a baby mistrusts all others is called separation anxiety. Most babies suffer from it in varying degrees between 7 and 9 months, even if they were chortling in the arms of any stranger just a month ago.
Don't worry, though. "Separation anxiety is a sign that your baby is emotionally attached to someone, and that's a very positive development," says Adair. Some evidence suggests that the onset of this powerful attachment to the most important people in their lives is associated with a spurt in brain development between 6 and 12 months. Studies also support the idea that your baby's earliest emotional bonds are the foundation for healthy relationships later on.
What goes into learning balance besides stronger muscles? The vestibular system. It consists of semicircular canals within the inner ear, plus a vestibule that houses important sense organs: tiny hairs called cilia, and minute bits of calcium carbonate called otoliths. Changes in your baby's head position cause the otoliths to tumble along the hair, which in turn provides the brain the information needed to make corrections in balance. Starting at around 7 months, the vestibular system becomes hyper-responsive, says Lise Eliot. It's the vestibular system that tells your beginning crawler how to adjust his trunk and legs so that his arms can pull him along more efficiently. Once he's upright, it tells him things like how far he can lean over before falling when he picks something up.
No matter how often you clean your floor, you'll still find yourself pulling small objects out of your baby's mouth. If there's a lost button on the floor, you can count on his finding it!
These explorations are a normal part of development. Babies begin to explore the world with their mouths even before birth; ultrasounds routinely show fetuses sucking their thumbs as early as 16 weeks. At birth, sensations in and around the mouth are the most highly developed, so once babies can reach for the world and take it in hand, they're eager to experience size, shape, texture, taste, and temperature by putting every object to the taste test. Mouthing peaks between 7 and 9 months and then declines steadily as babies become more adept at exploring the world with their hands. One study, by Jonathan Roberts and Martha Ann Bell at Virginia Polytechnic Institute and State University, in Blacksburg, noted that 8-month-old boys spend "an overall greater percentage of time mouthing" toys than girls of the same age. They attribute this to "faster brain maturation of female infants, who spend more time examining toys with their eyes."
While baby's in this stage, keep potential choking hazards away, and let him enjoy his hold on the world's delights and learn as he goes -- or chews.
Holly Robinson lives with her five children outside of Boston, Massachusetts.
Originally published in American Baby magazine, December 2005.
All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.