Chrissy Teigen Preps for Endometriosis Surgery on What Would Have Been Week of Son Jack's Arrival

She says she's feeling "a bit off" since "my little Jack would have been born this week"

Chrissy Teigen is sharing an update on what would have been the due date of her son Jack, whom she lost after 20 weeks of pregnancy back in September.

The cookbook author, 35, revealed on Instagram Sept. 30 that she and husband John Legend suffered a pregnancy loss, adding that they planned to name their boy Jack. The pair are also parents to daughter Luna Simone, 4, and son Miles Theodore, 2.

On Wednesday, Teigen tweeted that she's feeling "a bit off" since "my little Jack would have been born this week." She adds, "I truly feel kicks in my belly, but it's not phantom. I have surgery for endometriosis tomorrow...but the period feeling this month is exactly like baby kicks. sigh."

Alongside a video of her stomach appearing to subtly move, she writes, "Look at this. I'll pretend it's him saying hi - it never stops." Teigen, in a subsequent tweet, also asked her followers for insight into endometriosis surgery recovery, asking, "What is the recovery-difficulty level? like can I make soup after?"

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Teigen has been open about her grieving process since the heartbreaking pregnancy loss. In November, she said she was in a "bit of a grief depression hole," updating fans a few days later that while it had been "brutal" at the time, she felt like she was improving mentally.

Also in November, Teigen and Legend told PEOPLE they have been able to find a "little bit of sunshine" as they continued to grieve the loss of their son.

"You learn how to cope with it. I am very proud to say that there's multiple different therapies I'm using to hopefully become the same person that I was, and I'm okay with that," Teigen said at the time. "I'm okay with allowing myself to have bad days and good days."

Chrissy Teigen. chrissy teigen/instagram

Teigen, later in December, shared a photo of herself on Instagram, where she candidly spoke about her body, mourning that she will never be pregnant again.

"This is me and my body, just yesterday. Even though I'm no longer pregnant, every glance in the mirror reminds me of what could have been," Teigen wrote. "And I have no idea why i still have this bump, honestly. It's frustrating."

Then, noting that she is "proud of where this entire journey took my body and mind in other ways," Teigen added, "I love being pregnant, so so much, and I'm sad I never will be again."

"But I am lucky to have two amazing little ones who are transforming into big little people more and more every single day," said Teigen.