Kim Kardashian and Kanye West Welcome Baby Girl Via Surrogate

Kim Kardashian and Kanye West just had their third child via surrogate ... TMZ has learned.

Kim made the announcement, saying the surrogate gave birth Monday to a healthy girl weighing 7lbs 6oz.

TMZ broke the story ... Kim and Kanye used a surrogate because she has placenta accreta ... a life-threatening condition that created serious complications during the birth of her second child, Saint.

The surrogate lives in the San Diego area ... it's unclear if she gave birth there or at Cedars-Sinai in L.A. ... where the couple's other two children were born.