(CNN)Indianapolis Colts center Ryan Kelly and his wife, Emma, are mourning the loss of their baby girl, Mary Katherine, on social media.
Emma Kelly said that she was 19 weeks into the pregnancy when she went to the hospital last Wednesday after experiencing complications.
At the hospital, she says she learned that her daughter's heart stopped.
"I was told there was no other choice but to deliver our baby next," she wrote on Instagram on Monday. "Ryan and I spent almost 48 hours in the hospital.
"I labored for 24 hours with her before she made her entrance on December 17th. I was so angry at first that I had to deliver her, only for it to become the biggest blessing out of this nightmare. It gave Ryan and I the opportunity to hold our little Saint, Mary Kate, before officially saying goodbye to her.
"These 19 weeks with her opened our hearts & souls more than we ever imagined possible & I'm forever grateful we had some time, earth-side, with the little girl who made us mom and dad.
"She was tiny, perfect and incredibly loved from everyone who knew she existed. I don't think we'll ever understand why God decided to call her home when he did but our faith is unshaken. He knows better than we & she was needed back home, in Heaven."
Ryan Kelly expressed his feelings on Twitter.
"Nothing made me happier than being your Dad," he wrote. "You gave your Mom and I that gift. You were simply a miracle and always will be.
"I'm sorry you never got to open those sweet eyes and see us or take your first steps but you have angel wings now. You left this world too soon but we know God had a bigger purpose for you. Your mom and I find comfort knowing you're being loved on by your great grandparents.
"Thank you for watching over us and your future siblings. I'll forever wonder who you'd be today. Until we meet again my sweet girl, I love you."
In support, the Colts tweeted an emoji of a blue heart and butterfly.
Kelly missed the Colts' 27-17 win against the New England Patriots on Saturday night after his daughter's death.
After the game, Colts head coach, Frank Reich, said the team was honoring the family and Patriots head coach Bill Belichick extended his sympathy.
"We can all just show him the love and care that he has for this game," Colts cornerback Kenny Moore II said.
"We can show that same love and care for him off the field ... It just shows that life hits everybody hard at some point along the road. We're here thinking about Ryan and his family as they go through this tough time."