Kate Middleton Already Expecting Royal Baby No. 3! Find Out Why It's Been A Month Since She Was Last Spotted

Guests at a high-society wedding in Devon, England, were buzzing on Aug. 15 when Prince William showed up not with his wife, Duchess Kate, but instead with her sister, Pippa Middleton.  

That wasn’t the first appearance Kate has missed in recent weeks. In fact, the former Ms. Middleton hadn’t been seen in public in more than a month at that point!

As speculation runs rampant about the duchess’ reclusiveness, sources close to the royal couple tell Star that she has a good reason to stay out of the public eye. “She’s in the early stages of pregnancy with baby No. 3,” an insider reveals, “and she’s not taking any chances!”

“The Queen is delighted to be having another great-grandchild,” the insider said. “The monarch adores Kate and her babies.”

To help Kate through her pregnancy, helicopter pilot William plans to take time off from his job flying rescue missions with the East Anglian Air Ambulance service. “This time around, Kate and William are doing everything they can to ensure her pregnancy remains smooth and stress-free.”

Given Kate's history of difficult pregnancies—she was hospitalized with hyperemesis gravidarum, or acute morning sickness, in late 2012, when she was carrying Prince George, now 2, and she suffered from a similar condition while pregnant with Princess Charlotte, who was born May 2—it's no surprise that the duchess wants to take it easy this time around.

William even let a clue slip about his wife's condition recently. Sources say he confided to friends that he and Kate had been hoping to welcome a third child soon.

"It's a wonderful surprise," the prince noted, presumably referring to this third pregnancy, before praising his wife for her "amazing mothering skills."

Adding fuel to the fire, the couple have called off a planned February vacation with Kate's parents to the ultraexclusive Caribbean isle of Mustique.

"Kate's third baby is apparently due in late April or early May, so she'll likely be showing by the New Year," the insider explains. For now, though, Kate is resting at home and reveling in her baby joy. "She's always insisted she wants four children before her 36th birthday," the source added.