Get ready for the latest addition to the Kardashian clan. Kourtney Kardashian and her partner Scott Disick are making it a party of five: the couple is expecting their third child in December, People reports. The baby will join siblings Mason Dash, 4, and Penelope Scotland, who is 23 months old.

“She’s really excited but she’s nervous too,” a source tells People. “Three kids is a lot to handle! But she’s happy—she’s always wanted a big family with Scott.”

The couple recently started filming for the new E! show Khloe and Kourtney Take the Hamptons (a spinoff of Keeping Up with the Kardashians) in the New York resort area. Now we know why the oldest Kardashian daughter was glowing when we took notice of her outfit earlier this week when she stepped out for lunch with sister Khloé in tony Southampton, N.Y. She sported heels, white shorts, and a playful Ann Taylor top—clearly feeling great this time around! We can’t wait to see all her styles in the coming months.

Make sure to keep an eye out this summer for how she tackles maternity style on the beach, and take a look at more stylish celebrity moms-to-be in our gallery.