In a post shared on both of their verified accounts, the couple described their reactions to the death of their unborn child.
"We are shocked and in the kind of deep pain you only hear about, the kind of pain we've never felt before," they said. "We were never able to stop the bleeding and give our baby the fluids he needed, despite bags and bags of blood transfusions. It just wasn't enough."
They continued, "We never decide on our babies' names until the last possible moment after they're born, just before we leave the hospital. But we, for some reason, had started to call this little guy in my belly Jack. So he will always be Jack to us. Jack worked so hard to be a part of our little family, and he will be, forever."
Their emotional note also included a message to their lost child, issuing an apology for the circumstances of his death.
"To our Jack - I'm so sorry that the first few moments of your life were met with so many complications, that we couldn't give you the home you needed to survive," they wrote. "We will always love you."
Wrapping up their message, they thanked the world for sending positive energy their way amidst Teigen's earlier pregnancy troubles following her recent announcement.
"We are so grateful for the life we have, for our wonderful babies Luna and Miles, for all the amazing things we've been able to experience," they concluded. "But everyday can't be full of sunshine. On this darkest of days, we will grieve, we will cry our eyes out. But we will hug and love each other harder and get through it."