It's official -- North West is no longer the baby of the Kardashian-Jenner family!

Kourtney Kardashian confirmed she's pregnant Sunday on the “Keeping Up with the Kardashians” mid-Season 9 premiere episode “Let It Go." “I am pregnant!” Kardashian, 35, revealed in the reality-TV series’ supertrailer. Her longtime beau Scott Disick’s response? “What? Holy s---!”

The longtime E! starlet said her third pregnancy with Disick, 31, wasn't planned. The couple already have two children, Mason Dash, 4, and Penelope Scotland, 23 months. The newest addition to the family is expected to arrive in December. "They don't know the gender yet," a source told Us Weekly. "They just want the baby to be healthy."

The tabloid was the first to report Wednesday that Kardashian was with child and said that the reality starlet was only “a few months along” into her third pregnancy, but was already experiencing a new “pregnancy glow.”

While not much was shown of the pregnancy reveal, the Kardashians seem pleased that another baby is joining the family.

“This is amazing!” the family’s matriarch, Kris Jenner, 58, can be heard saying in the trailer while hugging her newly pregnant daughter. Kim Kardashian, 33, and her husband, rapper Kanye West, 37, welcomed their first daughter, North West, last June. Kim appeared shocked at news of her sister's third pregnancy, saying, “Are you kidding me?”

“Keeping Up with the Kardashians” airs Sundays at 9 p.m. ET on E!