When the Duchess of Cambridge was in the grip of crippling morning sickness in December, her weary husband admitted they felt like it would “go on forever”. Thankfully, Kate, 31, who is believed to be four-and-a-half months pregnant, is through the worst of it. So she and Prince William, 30, are celebrating by treating themselves to their last romantic holiday before their family becomes three.

Holed up in a $28,500-a-week five-bedroom villa on the Caribbean island of Mustique –which comes complete with six staff members and an infinity pool – you’d think they’d be keen for some time out alone. However, with Kate’s parents Michael and Carole and siblings James and Pippa staying just up the road in a villa of their own, the royal couple were happy to hit a public beach.

All eyes were on Kate’s adorable baby bump, proudly on display in her blue bikini. Many holidayers were abuzz with chatter about her curvier physique. “Most women dream of looking like her during pregnancy!” one exclaimed to US Star magazine… and Kate and Wills agree. “Kate said she loved the feeling of being pregnant and how it’s transforming her body,” said one local on the island, who stopped her in the street for a chat.

A friend of William’s adds, “He keeps telling his wife how amazing her new curves are.” The holiday, which many have described as a “babymoon”, is just what the doctor ordered after a tough first trimester, during which Kate was admitted to hospital with severe nausea. “They’re really making an effort to reconnect and go back to being a normal couple for a while,” the insider says. “They are aware that soon they’ll return to royal duty – but in the meantime, in Mustique, they’ve never looked happier.”

See all of the beautiful pictures of Prince William and Duchess Catherine on holiday in this week's Woman’s Day on sale Monday February 18, 2013.