“You should study not only that you become a mother when your child is born, but also that you become a child.”
I am not a mother with child, so I cannot directly speak of this experience. I could only imagine that this quote is referring to the fact that you are seeing and experiencing certain things for the first time, just as a child does. I also think it refers to the fact that you begin to see the world through your child’s eyes, with complete empathy. This is such a wonderful experience because how easily we forget the amazing experience of every little thing in the world for the first time.
We take too many things for granted, and have become so jaded that we no longer appreciate all of the little things in life, instead we look for things to complain about or desire. This insatiable desire is never satisfied, thus leading to suffering. This is a basic concept laid out in the Four Noble Truths.
We should embrace seeing and experiencing life as a child does, and we should study the Yin and Yang of becoming a mother, and a parent. We are both sides at once, there is no duality.