The heartbreaking story of Prince's son, Boy Gregory.

Prince is known for his catchy, upbeat songs, flamboyant sense of fashion and hip-thrusting dance moves. But behind the superstar’s out-there persona lay a shattering family secret.

The notoriously private pop icon, who died on Thursday at age 57, once had a son – but the little boy died in tragic circumstances.

Prince married his backup dancer Mayte Garcia on Valentines Day in 1996. Garcia, who was just 22 at the time to Prince's 37 years, became pregnant almost immediately.

The couple welcomed a baby, Boy Gregory, on October 16 1996– but sadly the child was born with congenital birth defects, reportedly linked to a skeletal abnormality known as Pfeiffer's Syndrome.

The generic condition is "characterized by the premature fusion of certain skull bones" which "prevents the skull from growing normally and affects the shape of the head and face," according to the U.S. National Library of Science.

Boy Gregory weighed in at a healthy 7 pounds, 12 ounces at birth - but died at just four days old, on October 23, according to the Minneapolis Star Tribune.

An autopsy was never confirmed, but doctors listed the baby’s cause of death as natural.

I can't even think of the words of what I'm feeling. This man was my everything, we had a family. I am beyond deeply saddened and devastated ... I loved him then, I love him now, and will love him eternally ... He's with our son now

A photo posted by Mayte Garcia (@maytejannell) on Apr 21, 2016 at 7:30pm PDT

Prince never confirmed publicly that his child had died. Bizarrely, he even appeared to deny the fact during an appearance on The Oprah Winfrey Show on November 21, 1996.

The couple went so far as to offer Oprah a tour of their son's playroom during the episode, even though the child had reportedly passed away weeks earlier.

You can watch a clip of Oprah's interview with Prince below (post continues after video):

According to a transcript, Oprah asked Prince, "What is the status of your — your — your baby, your pregnancy, your..."

To this, he replied: "Well, our family exists... We're just beginning it" and "we've got many kids to have, a long way to go."

Oprah's voiceover allegedly said: "And that's all The Artist and his wife choose to say at this time."

In June, 2015, Garcia told The Mirror she and Prince had simply been unable to process Gregory's death, and went on Oprah to show their resilience. "We had to show people that we were strong, that we had faith, and that we would try again," she said.

Post continues after gallery:

Garcia also revealed to The Mirror  that she had a miscarriage soon after Boy Gregory’s death. She told the newspaper: "To lose two babies is really scary... it really caught on me emotionally, physically, everything. It took me at least 15 years to get over it and still, to this day, I miss my son.

The couple split in 1998 and divorced in 2000. Garcia has named the loss of their babies as a reason for the split.

"I believe a child dying between a couple either makes you stronger or it doesn’t," she said.

"For me, it was very, very hard to move forward and for us as a couple I think it probably broke us."

Prince married once more– to Manuela Testolini in 2001– but never had any more children.

Although has never spoken publicly of his son's death or Garcia's subsequent miscarriage, his album Emancipation released poignantly includes the song "let's have a baby."

The song, released just weeks after Boy Gregory's death, includes the following lines:

"So long have I gazed into your eyes
Wonderin' what they'd look like on a newborn child
I cannot lie when my hand is on your thighs
I'm thinking, isn't it a miracle that life comes from inside?

"...I can't wait no more, let's have a baby
Don't you wanna?
What are we livin' for, tell me, tell me
Let's have a baby."

Prince and Garcia on stage (Photo: Getty)

Garcia, who now lives with her mother in Los Angeles, was photographed in tears on Thursday after hearing the news of her ex-husband's death.

"I can't even think of the words of what I'm feeling. This man was my everything, we had a family," she posted on Instagram on Friday.

"I am beyond deeply saddened and devastated ... I loved him then, I love him now, and will love him eternally ... He's with our son now."