My mother is the one of the index cases for this. They made a documentary for it and doctors wrote papers and books on her that helped jump start their careers. It was a big deal 20 years ago.
I was actually born a twin because since she had 2 uteri, there was an egg in each one. Though I was internally conceived a couple months after my brother, so when we were born at the same time I was actually born prematurely and nearly died. The doctors had predicted a 50% mortality for just one baby. Now 2 babies...they had predicted no survival. My mom was one of the first successful cases.