Kate Middleton's wardrobe - estimated to be one tiara and 30 outfits strong - during her tour through Asia with Prince William was expected to grab headlines.

READ MORE: William and Kate Prepare for Far East Tour

Now it's what her wardrobe could be hiding - a growing belly bump - that is making all the news. The 30-year-old Duchess, the subject of pregnancy rumors since the day she and Prince William wed last April, is sparking rumors once again that she may be carrying a royal heir after choosing water over wine at an official state dinner with Singapore's president and prime minister.

While William, also 30, and others raised glasses of wine to toast the country's Queen, Kate, dressed fashionably in a gown by Singapore-born designer Prabal Garang, twice politely declined and chose water instead, sparking a flurry of speculation.

Pregnancy rumors emerged in April, as the couple celebrated their one-year anniversary and last November, when the couple were reportedly preparing a nursery and after cameras caught Kate politely declining to sample a bite of peanut paste as she and Prince William visited a United Nations aid depot in Copenhagen.

"Things like this, people do look at them and wonder if they are signs," Victoria Murphy, royal correspondent for UK's The Mirror, told ABC News. "People are whispering and going on, "Is she pregnant? Is she pregnant?"

The rumors on this trip were further fueled by Prince William himself when he, for the first time, put a specific number on the size of the royal family he'd like to have, telling a fan he wants to have two children with Kate.

In May the prince, a helicopter rescue pilot with the Royal Air Force, told ABC News' Katie Couric he and Kate were eager to have children.

"I'm just very keen to have a family and both Catherine and I, you know, are looking forward to having a family in the future," the Duke of Cambridge said. Asked by Couric if there was anything else he wanted to share, he answered with a laugh, "You won't get anything out of me. Tight lipped."

WATCH: Prince William Opens Up to Katie Couric

The revelation came on Wednesday, the couple's second day in Singapore on tour of the Far East and South Pacific as part of the worldwide celebration of Queen Elizabeth II's Diamond Jubilee.

PHOTOS: Queen Elizabeth II's Diamond Jubilee Celebrations

In addition to the state dinner, William and Kate toured a Rolls Royce jet engine factory and unveiled the first engine produced by the plant, which opened earlier this year. The day before they visited the nation's Botanic Gardens where they viewed an orchid named after themselves and one named after William's late mother, Princess Diana, that she never herself got to see before she died.

During the rest of their trip, Kate and William will travel to four countries and are expected to engage with the locals through sporting activities, wearing traditional dress and even traveling by canoe.

PHOTOS: Will and Kate's Wedding Day

Kate will also mark a personal first on the trip, her first speech in a foreign country when she addresses staff and patients at a Malaysian hospice.