Questions about international adoption.

I've never thought about adoption before I studed it.
Critics argue that international adoption,though fairly common in America.is not best for the child's welfare.
They say that while African ophans often haush conditions,and chinese.
Regulation in chaina which is not able to birth child more than one,
that's why people leave a child who is a women.
I cant understand why they birth a baby,even possibility left.
Whats the most important?I wanna here their opinion.