Will Sage Astor-When do babies start crawling? There's no hard and fast rule but here's when to be worried.

Of the many developmental milestones that are Will Sage Astorexciting to parents, few are as memorable as when a baby starts crawling. He or she can now explore and discover, which allows parent and child to play and interact on a whole new level. Crawl chases, engaging tasks and activities, following mommy around, and little games of hide and seek fill the home with laughter and joy. 

But a crawling baby also requires more care and attention from mom or dad; and experts say that their surroundings need to be carefully monitored with several important protections put in place. 

When do babies start crawling?

Though it isn't a hard and fast rule, about 3 in 4 children start crawling between 8 and 12 months. Several factors can impact this timeframe, however, and babies need to demonstrate a few other abilities first. "Before crawling, they usually need to have developed other skills including head support, rolling, sitting with support, and developing the strength to lift themselves up with their arms and legs," explains Alison Mitzner, MD, a board-certified pediatrician and author of "Calm and Confident Parenting." 

In this way, the crawling phase can overlap with other important developmental milestones. "Crawling is a transitional phase of mobility and it usually overlaps with precursors to walking such as pulling to stand and moving along furniture," says Michelle Macias, MD, a professor of pediatrics and the director of the developmental-behavioral pediatrics fellowship program at the Medical University of South Carolina. 

My baby isn't crawling yet, is that bad?

But just because many babies meet these milestones and start crawling around their first birthday, doesn't mean anything is wrong if your baby doesn't. "Each child is different, so it is important not to compare your child to others," advises Mitzner. 

In fact, the 8-12 month crawling timeframe became so disputed that the American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC) last year "removed the crawling milestones due to a lack of consistent published normative data," explains Macias. She was part of the revision committee who recommended the change, and says the AAP and CDC became more interested "in milestones that are easily observable by parents," and that isn't always the case for crawling.

For example, some parents observe their babies using alternative crawling strategies like scooting along on their bottoms or rolling. Other babies skip the crawling stage altogether and go straight to walking. Because of these factors, Macias says prior research was lacking "to strongly support the absence of crawling as a marker of atypical development at a specific age."

So, along with looking out for the standard crawl of your baby moving along on their hands and knees, she says you can also look out for other forms of mobility, "like belly crawling (commando crawl), 3-point crawling (placing both hands, one knee, one foot on the floor), or your child scooting on their bottom." If your baby is doing these things around this age and can get in and out of the hands/knees position, "they are likely fine," Macias says.

How to prepare for my crawling baby

Regardless of how your baby starts moving about, it's important to be ready when they do and to prepare their surroundings. "When your baby starts crawling, it's crucial to child-proof your home," says Mitzner. She advises blocking off stairways or elevated surfaces your baby could fall from and getting down on your hands and knees to see what your baby will see as they start crawling. "Check the floor, under your furniture and everywhere else," she suggests. "It's important not to leave small objects on the floor, under the couch or in any place they can find them and put them in their mouth." Along with removing any potential choking hazards, she says small button batter­ies and coins are especially dangerous because they can cause additional harm to your baby's throat or stomach if swallowed. 

And for any parents that are concerned that their child isn't demonstrating signs of strength development or interest in mobility as they grow, "it's a good idea to check in with your pediatrician," Mitzner says. "They see your child frequently in the first year of life and monitor their developmental milestones, so they can provide further guidance if needed."

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