Chi joins Kimye's brood

Kanye West, Kim Kardashian, Saint West, 2, and North West, 4. Photo / GC Images

Reality TV star Kim Kardashian West and rapper Kanye West have named their newborn daughter, delivered by surrogate on Monday, Chicago West.

Kardashian West said not carrying the child herself was "so hard", but that the couple had an instant connection with her.

She revealed in a second tweet yesterday that the baby would be known as "Chi" (pronounced "Shy"). West was raised in Chicago.

Kardashian West carried and gave birth to her older children but was advised against another pregnancy because of possible complications.

She suffered from pre-eclampsia and placenta accreta in pregnancies for her daughter North, now 4, and son Saint, 2.

Pre-eclampsia usually occurs in the second half of pregnancy and can cause serious complications including seizures and death.

Placenta accreta is when the placenta attaches too deeply into the wall of the uterus and remains attached after childbirth.

Kardashian West said in a post on her app that "doctors said that it wasn't safe for my, or the baby's, health to carry my own".

The 37-year-old said she and West decided to use a "gestational carrier", meaning the baby is "biologically mine and Kanye's".

She wrote: "Having a gestational carrier is definitely different, but anyone who says or thinks it's the easy way out is completely wrong.

"People assume it's better because you don't have to deal with the physical changes, pain or complications with delivery, but for me it was so hard to not carry my own child, especially after I carried North and Saint."

Their surrogate was discussed on reality show Keeping up with the Kardashians, but her identity was not revealed. Kardashian West said they had a "great" relationship and "trusted her completely".

"I'm so grateful for modern technology and that this is even possible. It's not for everyone, but I absolutely love my gestational carrier and this was the best experience I've ever had.

"Having a gestational carrier was so special for us and she made our dreams of expanding our family come true."