"Finally you can add "helps delivers babies in living rooms" to my resume! It's been a miracle of a day... Auntie Katy aka Stylist Auntie," tweeted the Teenage Dream singer.
It would seem from her update that the new arrival belonged to her stylist, but the 29-year-old offered no further information about the baby.
There was no comment either from the American singer about her rumoured split from her musician beau John Mayer.
The pair are said to have split in the last few days, with Katy being the one to bring the curtain down on their union.
The stress over Katy's upcoming Prismatic tour is said to have caused a string of arguments. But according to sources the split is an amicable one and the couple plan to "remain friends".
John, 36, and Katy have had an on-off romance since they began dating in the summer of 2012.
They are thought to have split up in March of last year but were back together by the summer.
Katy and John Mayer are rumoured to have split
In December Katy gave her opinion on relationships as the couple debuted the video for their joint project, Who You Love, which features the pair riding a bull in the desert.
"Relationships are kind of like riding a bull – you hold on for dear life," said California Gurls singer Katy. "Sometimes you get a little a little buck here and there, but you get back on."
The same month, Katy admitted that her divorce from Russell Brand affected her relationship with John.
"I took a break from my boyfriend, not one that I wanted. I was like a splash of cold water to search inward on what was going on with me," she said.
"This is what led me to this new awakening, this realizing, if I don't do some self-love, I'm not going to be able to keep the love I want
"I still needed to deal with all of my ex-husband stuff. I hadn't. It's almost like if I kept talking about it, it would seem like I actually care about it. I don't."