The announcement was actually made at the end of Sunday's midseason finale of Keeping Up with the Kardashians, which dealt with Kim's ongoing struggles to conceive. A promo for upcoming episodes later this season showed Kim sharing the news with her sister Khloe. "I just got the blood test back, and I am pregnant!" Kim says.
Kardashian hinted at the big news earlier in the day on Twitter.
Kardashian and West, who recently celebrated their first wedding anniversary, are already parents to North, who will turn 2 next month.