Fans are freaking out after Kate Middleton was spotted without her ring - but there's an important reason why...

When Kate Middleton visited the Great Ormond Street Hospital yesterday there was a noticeable change to her royal look.

The Duchess wasn't wearing her famous 12-carat sapphire and diamond engagement ring.

Eagle-eyed fans were quick to spot that stunning sparkler was missing from her finger, leading some to speculate the royal's marriage to Prince William was on the rocks.

But there’s actually an important and fairly simple explanation as to why the Duchess decided not to wear the ring.

It turns out, the hospital has a policy on “minimal jewellery.”

“Since she would have to cleanse her hands thoroughly before touring the hospital’s wards and treatment areas, it is recommended to remove jewellery before entering,” People Magazine reported.

The mum-of-two is seldom seen without the priceless family heirloom, rarely taking it off since William proposed in Kenya in October 2010.

According to reports, Kate did put the ring back on after the morning visit.

During her appearances, Kate looked positively radiant giving us another glimpse of her growing baby bump!

The 36-year-old, who is already mum to four-year-old Prince George and two-year-old Princess Charlotte, is expecting her third child in April.

Think you know Kate Middleton? Why not test your knowledge on the Duchess...