beyoncejayztwinsgraziaImage: Getty

Beyonce and Jay Z’s newborn twins were born prematurely, a source has revealed to TMZ.

As per an insider, the baby boy and girl, who arrived last week on June 12 are still in hospital in special care and are “under the lights”.

While the source declined to elaborate on what exactly is wrong with the twins, being “under the lights” likely means the babies are being treated with bili lights, an ultraviolet light placed over a baby’s incubator to treat newborn jaundice, which sees a child’s skin and eyes slightly yellowed and is a fairly common condition, especially in premature babies.

According to Baby Center Australia, 50 per cent of full-term infants develop jaundice while 80 per cent of premature babies do.

Beyonce and Jay Z are yet to officially announce the birth of their new daughter and son, although the singer’s father Mathew Knowles confirmed the arrival – he posted a message on social media on Sunday, which was Father’s Day in the US.

“They’re here!” he wrote under a post reading “Happy Birthday to the twins! Love Grandad”.

Mathew made sure the post would go viral by hashtagging in #beyonce and #jayz.

Many members of Beyonce’s fan base the Beyhive came for Mathew after the post, accusing him of revealing the news without his daughter’s permission. However, others suspect Bey might’ve given her dad permission since it was Father’s Day.