It is the US singer and British actor’s first child together.
The two went back and forth on Twitter over a mistake in the description of little X Æ A-12 Musk's moniker.
The TV presenter said he's 'head over heels'.
The “Keeping Up with the Kardashians” star later chalked up her reaction to the news to hormones.
They couple also has a 1-year-old daughter.
How popular is the name Kim Kardashian and Kanye West chose for their daughter?
She says she's "going to explode" if he keeps buying gifts for their daughter.
Welcome Ella and Alexander!