TV star Jack Osbourne's wife Lisa has opened up about the heartbreak surrounding her 2013 miscarriage in a touching social media post to mark Pregnancy and Infant Loss Day.

The couple announced it was expecting a sibling for daughter Pearl in 2013, but weeks after going public with the news, Lisa revealed they had lost the unborn child.

They went on to welcome another girl, called Andy Rose, in June (15), but Lisa admits she is still mourning the loss of the son they planned to name Theo.

Taking to Instagram on Thursday (15Oct15), Lisa shared a card featuring two baby's footprints painted in blue and poured her heart out in the accompanying caption.

She wrote, "Today is national #pregnancyandinfantloss (sic) day. I don't talk about what happened to us much, and I've never posted this photo before out of fear that someone would say something mean or negative. I don't care anymore.

"I would have an almost 2 year old son now, named Theo. I never got to meet him, and this is all I have to remember him by... his tiny little footprints. It still hurts every day, and I will always love & miss him. He was a real baby, and he was mine.

"My heart goes out to my friends, family, and those of you I don't know that have suffered the loss of a baby. I love you all!"

The Osbournes wed in 2012, almost six months after Pearl was born.