Katy Perry has revealed the identity of the pregnant friend she helped give birth last week (26Feb14) - her sister, Angela Hudson.

The Roar hitmaker announced she had played midwife during a visit to a pal's home last Wednesday, taking to Twitter.com and writing, "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."

And, in a new interview with Australia's 2DayFm, the singer admits the new mum is her sister.

Perry explains, "My sister gave birth in her living room and I got to be kind of like an assistant doula, which, in a home birth, is kind of just there for support.

"I was in it! I mean I was holding... I probably shouldn't give too many details, but my sister actually is a true rock star. She gave birth in her living room without a single Advil (painkiller)."

Besides giving her sibling emotional reinforcement, Perry made sure she documented the entire experience for posterity.

She adds, "I was kind of like (director) Martin Scorsese, filming everything, you know, getting in there. She doesn't want to see that for, like, a year though."

Perry later took to Instagram.com to post a photo of two pairs of floral sandals, one for an adult and one for a toddler. She added the caption, "One for stylist auntie K and one for baby girl!"