Happy Birthday Kourtney Kardashian!

Though she's got plenty to celebrate--the reality star turned 33 Wednesday, and is expecting her second child with love Scott Disick--Mason's mama is skipping the big birthday bash, and opting for a low-key day instead.

PHOTOS: Kourtney's babymoon with Scott

"Kourtney and the fam just got back from Mexico," a source close to Kardashian tells Us Weekly. "Best trip ever! So that's it for [her birthday plans]."

Due later this summer, the pal says Kardashian is focused on resting and relaxing as she and Disick prep to welcome the newest addition to the Kardashian crew.

PHOTOS: Pregnant bikini bods

"They were at Joe Francis' house [in Mexico], just a big group of friends," the Kardashian pal shares. "Relaxing, a real vacation."

The vacay held extra-special significance for the Kourtney and Kim Take New York star: says the insider, "[This was the] last vacation before baby number two!"

PHOTOS: Awww! See how big Mason has gotten

Kardashian hasn't been shy about showing off her growing baby bump; in March, she escaped to the Dominican Republic with her family, where she flaunted her pregnancy curves in a sexy, tie-dyed two-piece.

"She's a little bigger this time [than she was with Mason]," Kourtney's younger sis, Kim told Us. "But she still looks amazing!"

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