What is a “BABY MAMA”?

Is this an offensive reference or is it a compliment / term of endearment?  What exactly is a "BABY MAMA"....and Why is it only Black Men use this term to identify a woman who has had their child?   It's obvious that it's a Mother of a Child...but why not just label the Mother...the Child's Mother...or My Son or Daughter's Mom?  There must be something more associated with the term BABY MAMA...what's your definition of BABY MAMA? (COMMENT BELOW)