Model Blac Chyna is reportedly pregnant with new fiance Rob Kardashian's baby.

The couple shocked fans and members of the extended Kardashian clan last month (Apr16), when it was announced Blac and Rob were planning to wed after a whirlwind courtship, and now it appears they are about to stun again.

Sources tell TMZ.com Blac Chyna is planning to make the baby news official on Sunday (08May16) - Mother's Day in America.

If the news is true, the child will be Blac's second - she's also mom to three-year-old King Cairo from her relationship with rapper Tyga, who is dating Rob Kardashian's half-sister Kylie Jenner.

Despite the weird family dynamic, Tyga recently congratulated his former fiancee on her new engagement, insisting he was happy for her.

Days after they announced their exciting news, he took to Twitter and wrote: "Everybody deserves 2 be happy. What some1 does for their happiness is not my concern, as long as it's not interfering wit my happiness (sic). It makes me happy to see the mother of my son happy."

Tyga and Chyna dated from late 2011 and they became engaged shortly after the birth of little King Cairo in October, 2012. The couple split in 2014.

Rob and Chyna have yet to comment on the report, while the Kardashian-Jenner clan also remained silent at press time.