Around four months, an infant is expected to be able to hold his head steady, without support, and push up to his elbows when lying on his stomach. He also may be able to roll from his stomach to his back at this stage of development. Around four months, an infant is also expected to push down on his feet when held in a standing position on a hard surface and bring his hands or objects to his mouth. At this stage of development, you may also notice that an infant can reach or swing at dangling toys and hold and shake small toys, like a rattle.
If at four months an infant can’t hold his head steady without support, doesn’t push down with his feet when held in standing position on a firm surface or doesn’t bring things to his mouth, nannies should mention their observations to the parents and encourage them to share this information with the child’s pediatrician.