Every photographer works to find their "go to" gear to help them create the story they want to tell in their photographs. Very quickly into my professional photography adventure, I found that I love prime lenses. If you don't know what a prime lens is, it is basically a fixed focal length. They are known for their sharpness and since I shoot pretty open, they have a amazing bokeh. With a zoom lens you can change your focal lengths.
In my bag you will find a 35 mm, 50 mm and 85 mm sigma art and sony lenses. (I'm a sony camera girl!) However, I mainly use my 35 mm since I just love the ability to stay close to my subject and get great sharpness. With newborns and babies, I always try to stay close especially if they are in buckets or sitting in props. This way I can ensure their safety.