Teigen wrote in a raw and emotional essay that she is healing from the loss, and is grateful for the outpouring of support she and her family have received.
"Even as I write this, I can feel the pain all over again," said Teigen.
Teigen offered the medical explanation doctors gave her: she had been diagnosed with partial placenta abruption.
"After a couple nights at the hospital, my doctor told me exactly what I knew was coming -- it was time to say goodbye," said Teigen.
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Teigen had some stern comments for those who criticized her for posting pictures after Jack's death.
"I cannot express how little I care that you hate the photos. How little I care that it's something you wouldn't have done," Teigen said. "I lived it, I chose to do it, and more than anything, these photos aren't for anyone but the people who have lived this or are curious enough to wonder what something like this is like. These photos are only for the people who need them. The thoughts of others do not matter to me."
Teigen said she chose to write this essay because she knew it was something she needed to do for herself before she could move on from the tragedy.
"Jack will always be loved, explained to our kids as existing in the wind and trees and the butterflies they see," said Teigen. "Thank you so much to every single person who has had us in their thoughts or gone as far as to send us your love and stories. We are so incredibly lucky."
To read Teigen's essay, click here.