Reports have confirmed what has caused health issues for Beyonce's twins

Beyonce and Jay Z's twins are reportedly receiving treatment for jaundice after being born prematurely.

Family insiders told TMZ the boy and girl, who have been in hospital since their birth eight days ago, are "under the lights" - a common treatment for jaundice.

TMZ reported yesterday that the newborns have spent the week in hospital with a "minor issue" because doctors don't "feel comfortable" releasing them.

However, they are expected to be okay.

On Sunday, which is Father's Day in the US, Beyonce's dad confirmed the arrival of his daughter's babies.

"They're here! #beyonce #twins #jayz #happybirthday," Mathew Knowles wrote on Twitter, posting a card saying: "Happy birthday to the twins! Love, Granddad."

Beyonce and Jay Z, haven't come out to the public yet in regards to anything official as of yet. but the world is waiting intently for the first photos of the twins with the mystery.

• This article was first published on nzherald.co.nz and is republished here with permission.