Haylie Duff is going to be a mom!

The 29-year-old and her fiancé Matt Rosenberg revealed on Tuesday that they are expecting their first child.

"Happiest girl in the world! Finally can let everyone know that Matty @mr_sts and I are expecting! #BabysFirstJordans," Duff wrote on Instagram, alongside a photo of an adorable pair of baby shoes.

Duff has no doubt been brushing up on her mommy skills while spending time with nephew Luca, the son of her sister Hilary Duff.

In fact, Haylie posted a sweet photo of her and Luca making cookies on Thanksgiving last week.

Hilary tweeted her excitement over her big sister's big baby news on Tuesday.

GUYS I'm going 2 be an auntie ‪@haylieduff & ‪@matt_sts are going to be the best parents to a sweet baby&luc will have a partner in crime

Duff and Rosenberg announced their engagement in April this year. Now that the pair has a baby on the way, how will the impending edition to the family affect their wedding planning?

Well, the couple hasn't commented on that just yet but Duff did admit to Access Hollywood that she and Rosenberg are taking their time when it comes to organizing their upcoming nuptials.

"Are we slacking?" joked the actress. "We're just really enjoying this phase of our relationship. I feel like, so many people, you get engaged and then it's like, 'OK, we have to get married within a year' or whatever it is...We're kind of just, like, enjoying being engaged. It's fun to be a fiancée."

And the couple looks happier than ever. Duff shared a photo of her and her sweetie on Instagram last week.

"Happy Anniversary to the greatest man I know. I'm lucky to be yours. @mr_sts," Duff captioned the photo.

Congrats to the parents-to-be!