North and Saint have a new baby sister!

Kim Kardashian West and Kanye West welcomed their third child on Monday, Kardashian announced via her app and website Tuesday. On Friday, she revealed the baby's name: Chicago West.

"Kanye and I are happy to announce the arrival of our healthy, beautiful baby girl," Kardashian wrote. "We are incredibly grateful to our surrogate who made our dreams come true with the greatest gift one could give and to our wonderful doctors and nurses for their special care. North and Saint are especially thrilled to welcome their baby sister."

Chicago (who they'll call Chi [pronounced "shy"] for short) joins sister North, 4, and brother Saint, 2. West is from Chicago, in case you were wondering.

The reality star and the rapper opted to use a surrogate for the pregnancy due to complications Kardashian experienced during her previous pregnancies. Her struggle to conceive a third child were well documented on Keeping Up with the Kardashians, which celebrated the announcement of her sister Khloe Kardashian's pregnancy the same day Kardashian and West welcomed their newborn daughter. Kardashian's half-sister Kylie Jenner is also reportedly expecting her first child.

Kanye West and Kim KardashianKanye West and Kim Kardashian