This is a terrible story. As readers what are we supposed to understand from this?
Did anybody ask Hagar what she wanted?
Did she want a baby?
Did she love Abraham?
Did she even have a choice?
God doesn't even show up as a guide to Abraham: "No Abraham, thou shalt not rape Hagar. She is a human being just like you and deserves dignity and respect".
No! the reader is left to think whatever they will, including such clap-trap as:
"Abraham had the right to rape Hagar, she is a slave and as such is his property to do whatever he wills". What load of $*&%, human life is to be respected not used as surrogates.
Another point is if God loved Abraham so much why didn't He give Sarai new ovaries right there and then instead of several years later (Gen 17:16)?