Evidence for God from Science

I was having a discussion, and the person asked the gender I was assigned at birth. I said gender is never assigned at birth, it is determined prior to birth (hence all of those gender reveal parties) and confirmed at birth. To say gender is assigned implies the person assigning had a say in which label to give, when they do not. They make a determination based on the physical characteristics the baby has, and use that determination to label the baby male or female.
Yet it seems everybody, even in the professional community seem to use this term; gender assigned at birth. Why is this? Your thoughts?