A: Rachelle, I can just see you cheering your 5-month-old son in his baby gymnastics! It's natural for you to want to see him progress through the many developmental steps this year: rolling over, sitting up, crawling, and walking.

Actually, a recent study found that babies are rolling over and crawling at a later age now that parents are putting their babies to sleep on their backs, as recommended to prevent Sudden Infant Death Syndrome (SIDS). Whereas the child development books describe babies typically rolling over around 3-5 months of age and crawling around 6-9 months of age, babies today may be 2-3 months later with those skills. The experts think this is because babies who sleep on their back have less practice on their tummies arching their backs and pushing up with their arms; and, they can see so much and reach out for things on their backs, so they have less incentive to roll over. Also, your baby is on the larger side, and it might take a little more time and strength for him to roll over.

Experts say it is not a problem for babies to roll over and crawl a little later. In fact, they found that babies ended up walking around the same time, 10-14 months of age; and approximately one-third of babies began walking without ever crawling.

It's a good idea to balance your baby's time on his back with enough time playing on his tummy during the day when he's not sleeping. Try offering him toys just outside his reach to encourage him to roll over and crawl for the toy. And cheering him on is good, too!

If your baby is developing normally, he'll probably roll over within a couple of months. From what you said, it sounds like he's close already. Take this extra time to crawl around your house and make sure it's child-proofed for safety. If you're still concerned about your baby's development, be sure to talk with your pediatrician about it.