Kanye West and Kim Kardashian West on September 9, 2016 in New York City. Dimitrios Kambouris/Getty

West, party of six! Kim Kardashian West and Kanye West's family just expanded. The couple has welcomed their fourth child, a son born via surrogate, Kardashian West announced Friday. "He's here and he's perfect!" the reality star and beauty mogul tweeted.

While the newborn's name has yet to be announced, Kardashian West did reveal one detail. "He's also Chicago's twin," she tweeted. "lol I'm sure he will change a lot but now he looks just like her."

The new child joins North, 5; Saint, 3; and Chicago, 1. This is the couple's second child via surrogate. Kardashian has been open about needing to use a surrogate, due to suffering preeclampsia during her first two pregnancies.

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Kardashian broke the news about her fourth baby in January, when she appeared with her sisters on "Watch What Happens Live with Andy Cohen." The Bravo host had just announced he was expecting a baby boy via surrogate.

Earlier this week, Kardashian West tweeted a screenshot of a message her husband sent, in which he praised some of her accomplishments: "This is your life. Married with four kids. Get people out of jail. Cover of Vogue. Go to church every week with your family. Dreams do come true."

Morning Texts ✨ pic.twitter.com/9elTakkTee — Kim Kardashian West (@KimKardashian) May 6, 2019

Kardashian West has been very busy as of late. She recently helped free 17 people from jail and revealed she was studying to take the bar exam and become a lawyer.