Aaron Hernandez's Fiancee Shayanna Jenkins Says She's Pregnant

The woman who was engaged to Aaron Hernandez -- the mother of his daughter -- has announced she's pregnant ... but the big question -- who's the daddy?

Shayanna Jenkins broke the news on Instagram ... saying, "Many of you have had speculated that I may be expecting another miracle which is very accurate."

FYI, Hernandez died in April 2017 after he hanged himself in his prison cell. In theory, he could have frozen his sperm for her to impregnate herself at a later date.

If Jenkins is in a new relationship, she hasn't gone public with it -- in fact, the last time she posted a photo of a man on her IG it was Aaron Hernandez.

Still, Jenkins is shedding SOME light on her pregnancy ... saying, "I wanted to have a moment for myself alone with my daughter ... we are beyond excited about the new addition and chapter we will soon begin."

Jenkins did not reveal how far along she is or when the baby is due -- but did say she's having a girl.

"I couldn’t be a luckier woman to have such a perfect little girl that’s prepared to become the best big sister , and even more blessed to welcome another babygirl to our home."

"BabyG we are very excited to meet you !!! Mommy and sissy will continue to wait patiently for your arrival."

Hernandez left a suicide note to Jenkins calling her his "soul-mate" and telling her that she would be "rich" after his death.

We reached out to Jenkins to find out more -- but so far, we haven't heard back.