PARO (AFP) - In the serene grounds of Paro Ugyen Pelri Palace in the remote Himalayan kingdom of Bhutan, a young couple pose for the camera, his arm resting on her growing baby bump.

Queen Jetsun Pema, 25, and King Jigme Khesar Namgyel Wangchuck, 35, delighted the nation in November when they announced they were expecting their first child, a son.

A new photograph - the January instalment of an online calendar released by the Royal Office - shows the expectant couple sitting in the secluded palace woods dressed in traditional bright robes.

"This year, our happiness is immeasurable as we look forward to the birth of our prince. It is going to be a beautiful year in Bhutan," the Royal Office said in a statement.

Known as the "last Shangri-La", Bhutan, home to just 750,000 people, famously shuns conventional measures of economic wellbeing, instead compiling a Gross National Happiness index.

The hugely popular fifth Druk Gyalpo, or Dragon King, studied in Britain and the United States and was officially crowned king in 2008 after his father abdicated two years earlier.

He married Queen Pema in 2011 in an elaborate fairytale wedding ceremony that was the biggest media event in Bhutanese history.

A majority Buddhist nation, Bhutan had no roads or currency until the 1960s, and only began admitting foreign tourists in 1974 - but has since developed rapidly.