Her Grammy-winning spouse made sure to chime in as he playfully commented underneath "Maury will have the final word on this" referring to TV host Maury Povich who is famed for his "You are NOT the father" catchphrase.
Chrissy even gave her fans a glimpse of her baby bump as she took to Snapchat with a photo of her wearing a skintight black tube dress.
She wrote: "Very excited to not have to hide this anymore. Everyone I told first was like 'uh yeah, we knew thanks'".
Chrissy and John, 38, married in 2013 and welcomed Luna in April 2016.
The Sports Illustrated beauty has been open about her desire to expand her family, recently telling E! News she would love to be "pregnant for the rest of her life".
She shared: "I feel good, I feel good, we're still trying ... I'm going for I mean hopefully in the next few years because for me I really want to just knock 'em out. That's my dream, I want to just be pregnant kind of for the rest of my life. Not for the rest of my life, but the rest of my fertile life. So we'll see."
Whilst John added: "We want more, we'll hopefully have another one in the near future. We're working on it."
She shared: "I probably think about it more than anybody. I cannot wait to have the biggest family. Everybody is curious. They're like, 'When are you going to do it? When are you going to do it? When's the process going to start?'
"It's so fun absorbing baby Luna right now. I think I'm enjoying my time absorbing and seeing everything - all her new little steps and new moments - and being there for them ...
"Every day it's something new with her. More than anything, I love seeing her little palette. She will eat anything and everything. I just think it's so fascinating. You give her the whisk and she knows exactly what to do the second you teach her. It's really cute."
Chrissy Teigen and John Legend with their daughter Luna. Photo / Getty Images
In August Chrissy revealed she'd given up alcohol in hopes of conceiving a second child and was embarking on IVF treatment.
She told Cosmopolitan: "I used to think it was kind of nutty to have to go totally sober.
"But now I get it. I don't want to be that person... I have to fix myself. I was, point blank, just drinking too much," the Lip Sync Battle host admitted.
"I got used to being in hair and make-up and having a glass of wine. Then that glass of wine would carry over into me having one before the awards show. And then a bunch at the awards show.
"And then I felt bad for making kind of an ass of myself to people that I really respected. And that feeling, there's just nothing like that. You feel horrible. It's not a good look for me, for John, for anybody.
"A lot of stuff's about to come," Chrissy continued. "We're going to try to have a child. This is for us to try to get in the zone of 'let's travel, let's be away together, let's see our closest friends,' and then we're going to have to do something super hard, which is the IVF process, all over again."
Of beginning the fertility treatment again John said: "I wouldn't say we can't conceive naturally, but I would say that it's enough of a challenge where it felt like we needed help.
"We're lucky that we're living in an age where we can conceive in other ways. [IVF] brought us Luna and hopefully it will bring us a few more awesome kids, too."