The news came just days after it was learned that Khloé's sister, Kylie Jenner, was pregnant and that rapper Travis Scott, who has been dating the 20-year-old reality star since April, is the father. Her baby is due sometime in January or February.
Khloé's older sister, Kim Kardashian, 36, is also expecting a child in January. This will be Kim's third child with Kanye West, and the couple is using a surrogate.
While it's not clear when Khloé's baby is expected, a source told BuzzFeed News that it was after Kylie's due date.
This will be Khloé Kardashian's first child. Tristan has a 9-month-old son, Prince, with his ex-girlfriend Jordan Craig.
On Keeping Up with the Kardashians, Khloé talked about having kids with Tristan. "He wants to have about five or six kids with me and that’s lovely," she said. "We could start at one and we could grow from there."