This Is Us: Chris Sullivan on why Kate hasn't told Toby she's pregnant

This Is Us dropped some major news on its viewers at the end of Tuesday’s episode: The poppy seed is now a lentil.

Now, for those of you who missed the episode and have no idea what we’re talking about, we will be more specific: Kate (Chrissy Metz) is pregnant. The newly aspiring singer is six weeks along, as we learned at the end of the episode — after spending most of the hour thinking, like her fiancé Toby (Chris Sullivan) did, that she was especially concerned with healthy eating and exercising because she was trying to fit in a dress for a singing gig at a bar mitzvah.

What was Sullivan’s reaction when he first heard about the plan, which creator Dan Fogelman says has been in the works since season 1? “Knowing Dan and the writers, I was like, ‘Oh, yeah. That makes sense,’” chuckles Sullivan. “I was excited for the two of them. I think they’ll make good parents.”

Kate issued a sigh of relief and then a smile when the doctor told her that the pregnancy was progressing on schedule, but she wasn’t ready to celebrate the good news with anybody just yet, even Toby. “For their situation, it could be any number of reasons,” says Sullivan. “The state of their relationship, they’re not married yet, pregnancy is a delicate thing. The couples I know wait until the first trimester’s over sometimes because there are a lot of things that can happen. Kate has a history of not wanting to get her hopes up for things.”

What can he hint about Toby’s reaction when he finally gets the news in Tuesday’s episode? “I think Toby’s a pretty positive person,” deadpans Sullivan. “He seems to have pretty upbeat reactions to most things, so I can’t imagine he would react any differently to that.”

Clearly, this turbo-injects a new dynamic into their relationship, which they agreed to take slowly. (In fact, they just moved in together.) “Everybody has to take curveballs as they come in life and hopefully have the ability to adjust their plans,” he says. “Hopefully Toby and Kate will stay focused on each other, and we’ll see how it all comes out the other side.”

While we wait to see the other side of this big life transition, Sullivan teases of the Kate-Toby rollercoaster in the next few episodes: “I think it’s going to be a lot of thinking on their feet — and trying to do what’s best.”

What’s best for you right now is to read a Q&A with Metz about Kate’s pregnancy right here, and then see what the show’s creator had to say about this game-changer over here.

This Is Us airs Tuesdays at 9 p.m. on NBC. For more This Is Us coverage, follow us on Flipboard.