Kardashian filed for divorce in October 2011 after 72 days of marriage, but her split to Humphries isn't official yet.
Under California's Family Code, a man is presumed to be the natural father of a child if he is or has been married to the mother and the baby is born during marriage or within 300 days of it ending.
Kanye West announced Kardashian's pregnancy earlier this week during a concert in Atlantic City, New Jersey. The rapper asked concertgoers to congratulate his "baby mom."