My 4-m.o baby is too lazy to roll-over unlike other babies who are in the same age as her. Should I be worried?

While some four-month old are able to roll over, not all are. Like what Jamie mentioned, not all babies are the same. You can try to practice with her by placing toys that are just beyond her reach while she is lying on her back. She will soon realize that rolling to her side will help her reach the toy. Here is a full list of developmental milestones usually achieved by babies at four months of age. Make reference to it just as a guide. http://www.cdc.gov/ncbddd/actearly/milestones/milestones-4mo.html According to the article, you should keep a lookout for these signs and consult your doctor if your baby: - Doesn’t watch things as they move - Doesn’t smile at people - Can’t hold head steady - Doesn’t coo or make sounds - Doesn’t bring things to mouth - Doesn’t push down with legs when feet are placed on a hard surface - Has trouble moving one or both eyes in all directions If you notice any behavior that is out of the ordinary, always consult your doctor for a peace of mind.