The smooth movement of hands to mouth (with objects now in tow!)
Your baby is likely to have been putting their hand in their mouth since they were born, but you might notice now that they can do this more accurately, bringing their hand up quite smoothly. When they are holding a toy, they may also try to put it into their mouth; of course they won't be able to get this right every time and might sometimes bump their chin rather than reaching their intended destination.[1]
Developing control
Your baby’s fine motor and gross motor skills are closely linked as initially they will use movements of their arm to position their hand to grasp and explore items.[1]