Robert Griffin III & Fiancee Welcome Baby Girl!!!

Robert Griffin III is a proud papa for a second time ... his fiance just announced the birth of their daughter.

Grete Sadeiko announced Tuesday she gave birth to Gloria who was born Sunday and came in at a healthy 6 pounds, 12 ounces.

Grete wrote on Instagram, "Couldn't have done it without this man by my side, my backbone. Trying to make me laugh every way possible and keeping me entertained through all the pain and doing everything to make me smile and get through this. You deserve a medal baby!"

The NFL and Florida State track star got engaged back in May ... on the same day she announced she was preggo with Robert's kid.