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.Baby's Body Is Ready
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!