Alanis Morissette didn't know she was pregnant until a doctor told her.

The 'You Oughta Know' singer - who this week announced she is expecting her first child with her rapper husband Souleye, real name Mario Treadway - went to see her physician for another reason when he gave her the happy news.

During a TV interview with Chelsea Handler, she said: "I went to the doctor and he said, 'Well this looks like the scan of a pregnant lady.'

The 'Chelsea Lately' host then put it to Alanis that she had "obviously gone to the doctor because you thought you were pregnant?"

To which the Rock Star replied: "No actually I thought I wasn't. But I mentioned in passing that I was a bit late, so he said, 'Well let's just take a quick look.' "

Even after being told by her doctor she was expecting, 36-year-old Alanis - who is five months into her pregnancy - still couldn't believe it.

She explained: "I said, 'But there's still a chance I'm not though, yes?' And he said, 'About as much chance as me getting a sex change.'

"And I said, 'So when are you getting a sex change!?' "

The musician also revealed she was instantly attracted to Mario the first time she met him at a meditation ceremony at her house.

She said: "He walked in and I thought to myself, 'Wow he's incredibly sexy.' "

Alanis - who married Mario at her Los Angeles home in May after dating him for just eight months - has also tweeted her followers her joyous news, saying: "Yes, happy news, i'm pregnant :) we're so excited to start our family.... xo a (sic)"