From birth, a baby has certain reflexes, especially the need to suck and the grasping reflex. Sucking is a natural, innate requirement in infants. Sucking helps babies to be reassured and sleep.
The grasping reflex only appears during the first few months of the baby's life, a baby bends fingers when an object is placed in its hand.
At birth, a baby has weak muscle tone and cannot support its head. This is why the head must be supported during the first few months.
About 4 months, the baby can lift up its head when it is lying down on its stomach, he/she starts to change position him or herself, on the back, he/she can roll on to its side. Finally, he/she can turn its head in the direction of an object.
About 5-6 months, the baby can hold a toy between its fingers and hold on to its feet.