UPDATE: It seems that Kourtney was just playing coy, when she casually tweeted about a water birth last night.
Today the reality star tweeted that she only witnessed a water birth, writing, "Witnessed a water birth last night with @KhloeKardashian. What an experience! All I can say is WOW!"
PREVIOUSLY: Kourtney Kardashian is due to give birth any time now, and it may have already happened.
On Thursday night, the 33-year-old reality star tweeted, "Chick-fil-A and a water birth. No big deal."
That tweet might have been Kourtney's super-casual way of sharing the good news with the world. If she has, in fact, given birth, the new addition makes Kourtney and boyfriend Scott Disick's 2-year-old son, Mason, a big brother.
The couple announced the pregnancy with a cover story in Us Weekly in November, and Kourtney expressed how excited she was to be adding another member to their family, telling E! News, "Scott and I are so excited to announce that we are expecting our second child and are thrilled to be expanding the love in our family."
In February, the reality star revealed that Mason was going to have a little sister.
"We feel so blessed to be having a little girl and to be able to share this new experience with Mason," Kardashian told E! after announcing the news on OK! magazine's cover.
The tweet sparked hundreds of congratulatory messages from fans, but so far neither Kourtney nor any of the Kardashians has confirmed the good news.