Rob Kardashian has vowed to shed his "pregnancy weight".

Rob Kardashian's Instagram post

Rob Kardashian's Instagram post

The 29-year-old 'Keeping Up with the Kardashians' star is expecting his first child with his fiancée Blac Chyna in just four weeks and has vowed that he and his partner will be "snapping back" into shape because he is "done" with carrying the extra pounds he has put on sharing in the same calorific delights Chyna has been gorging on for the baby.

The father-to-be shared a picture of him and the model - who flaunted her pre-body frame in a skimpy blue printed bikini - to his Instagram account, which he captioned: "Oh yeah we snapping back lol,,, baby will be here in 4 weeks and I'm done with carrying this pregnancy weight me and my baby gonna be righttttttt ,,, MOTIVATION TIME‼ we almost there Chy F******K Chy looks so bomb here aghhhh (sic)."

Although 28-year-old Chyna - whose real name is Angela Renée White - previously admitted she wanted to gain "100lbs" during her pregnancy, she plans to follow a "strict" eating and fitness regime as soon as she gives birth to her second child, which is due on November 16.

Speaking previously, Chyna - who already has four-year-old son King Cairo with her former partner Tyga, who is dating Rob's half-sister Kylie Jenner - said: "My goal is to gain, like, 100 pounds this pregnancy. I'm gonna tear it up, then I'm gonna snap back. Strict diet, waist training, detox tea and working out."