The 'Love You Like A Love Song' singer axed the gigs over a "family emergency", with her representative confirming to Gossip Cop that her mother Mandy had lost her unborn baby.
The child would have been Gomez's first sibling and Mandy's first child with her second husband Brian Teefey.
The 19-year-old's cancelled Christmas concerts were due to be held in Chicago and Seattle over the weekend.
Upon announcing her mother's pregnancy in November, Gomez claimed that she was "the happiest girl in the world".
Her boyfriend Justin Bieber recently took a paternity test to prove that he is not the father of fan Mariah Yeater's infant son.