Please please please do not compare human fertility to ball python fertility. Humans being primates we are by definition mammals and therefore don't lay eggs. This makes our reproduction different enough that I think any comparison is going to be pointless.
That being said woman die during child birth all the time and many many more would if not for expert medical care. Extremely young women as well as extremely old woman (over 35, sorry ladies) put themselves and there unborn children at greater risk. Weight also plays a huge role in woman's fertility.
I am not making any judgment calls here at all. I just think you have to ask yourself why you are doing what you are doing and see how you feel about it.
Personally I would not breed a female BP until her 3rd breeding season and only after she was over 1500 grams. I base this solely on the prevailing wisdom of books I have read and sites like this. I am not in the habit of rolling the dice with my animals health and well being.