Kourtney Kardashian has fuelled speculation she and Scott Disick are trying for a fourth child together in a new Keeping Up with the Kardashians teaser.

The trailer for the 19th and penultimate season of the reality show dropped on Tuesday and fans were stunned as Kourtney's sisters, Khloe and Kim Kardashian, quizzed her about potential baby news with Scott, the father of all three of the star's kids.

"Scott‘s like, 'We’re going for baby number four'. Is that serious I want to know?" Kim queries in the trailer.

Khloe asks directly: "Are you pregnant?"

The clip ends with a shocked Kourtney staring at her sisters.

The news comes amid rumours Scott and Kourtney are back together again after he officially broke up with model Sofia Richie, his girlfriend of two years, in August.

Kourtney and Scott originally began dating in 2006 after meeting in Mexico, dating for nine years until 2015. Scott has been a fixture on Keeping Up with the Kardashians since 2007 but has had a textured life in the spotlight, checking in and out of rehab on multiple occasions.

The couple already shares Mason, 10, Penelope, eight, and Reign, five.

The premiere episode of the new season of Keeping Up with the Kardashians airs in the U.S. on Thursday.