Kim Kardashian and Kanye West are reportedly expecting their fourth child

Kim Kardashian West’s surrogate is reportedly pregnant again.

The 38-year-old reality star and her rapper husband Kanye West - who already have North, five, Saint, three, and Chicago, 11 months - have turned to surrogacy again after Kim was advised not to have anymore pregnancies because of the complications she previously suffered when expecting her first two children.

While pregnant with North, the brunette beauty suffered from pre-eclampsia, a complication characterised by high blood pressure. She also had placenta accreta in both pregnancies, which occurs when the placenta attaches too deeply in the uterine wall.

According to a source close to the celebrity couple, the Keeping Up with the Kardashians star and her spouse have used their remaining fertilised embryo and should be welcoming a baby boy into the world in May.

Kim has previously been very open about her desire to have a fourth child.

Speaking about surrogacy, she said: "I would have maybe one more."

"I enjoyed the surrogacy process. When it came time to breastfeed, I realised it was the best decision I have made."

Previously, it was revealed the couple had found someone willing to carry Chicago for them for US$45,000 (NZ$70,000).

It was also reported that on top of the $45,000, Kim and Kayne would give the surrogate - who hails from San Diego - an extra US$5,000 per child in the event of a multiple pregnancy, as well as an extra US$4,000 if if the surrogate loses reproductive organs in the process.