KATE MIDDLETON is terrified the royal family is putting her unborn child at risk with a hectic schedule of appearances – and close friends are begging her to get some rest before her pregnancy ends in tragedy.

While the future queen has been wearing a brave smile as she tackles her seemingly endless list of royal engagements and appearances, a royal insider tells The ENQUIRER that “all Kate really wants to do is lay low at home, put her feet up and watch movies like the rest of her pregnant friends.”

Kate, 31, who is five months along, however, feels obligated to pick up the slack for Queen Elizabeth, 86, who is recovering from a mystery illness that required an overnight stay in the hospital.

And that, says the insider, means Kate’s calendar won’t be clear anytime soon!

On March 17, Kate – who married Prince William in a lavish ceremony on April 29, 2011 – attended a St. Patrick’s Day parade and ceremony in southern England. Three days later, she joined the queen and Prince Phil­ip on a tour of the London subway station to commemorate 150 years of the country’s subway system.

On March 22, she was in northern England, braving snow and subzero temperatures, for an engagement with scout troops.

Kate was next scheduled to attend the opening of an outdoor royal hubby was to be by her side.

It’s a busy schedule for anyone, let alone a woman who’s already had trouble in her pregnancy. Royal author Nicholas Davies, a friend of the late Princess Diana, told The ENQUIRER: “Kate suffered a horrendous early pregnancy with agonizing morning sickness and might have lost her baby.

“Now she’s become the royal workhorse and it’s obvious to anyone that she’s burdened with more engagements than is safe for a heavily pregnant woman expecting her first child.

“Her schedule is ridiculous. It’s bound to create stress, and it’s high time the palace recognized the danger. There’s a real chance Kate could collapse.”