Sources tell us Remy was suffering from excessive bleeding Tuesday night and went right back to the hospital. The post-birth complications necessitated emergency surgery.

As we reported ... Remy and Papoose announced the birth of their daughter on social media, but didn't disclose her name. Papoose called it "tough labor." Mind you, Remy went into labor at age 38 -- Papoose is 40 himself -- and revealed last year she had recently suffered a miscarriage.

Amazingly, we're told she delivered her new baby naturally.

As for how things went on the operating table, Remy received blood transfusions ... and the good news, we're told the surgery was a success. We're told she's doing well, and she's expected to be released in the next day or so.

Get well soon, RM. And, of course, congrats on the kid.