TOKYO, JAPAN - Three years ago, a poster of a nude and heavily pregnant Britney Spears sparked concern in Japan before it was displayed in Tokyo's subways because it was considered "too stimulating" for young commuters.

But today, an increasing number of women who have just one child later in life are flocking to photo studios to have their pregnant bellies photographed to celebrate their bodies during a once-in-a-lifetime experience.

"I was so happy during my pregnancy," said 40-year-old Kumiko Yoda, who gave birth to a boy on July 19. "This moment will not come back to me again and these pictures are for my own enjoyment."

Yoda was encouraged by a friend who showed her maternity nude photos that she had had taken of herself and just one month before her baby was born, Yoda discovered maternity photo studio "Ixchel" in Tokyo.

Initially, she posed showing only her belly but as the all-female staff at the studio helped her relax, she posed nude for the camera. The black-and-white pictures are displayed in her home.

"Whenever I see these pictures, I can recall how I looked and how happy I was when I was pregnant," says Yoda.

The trend of taking pregnant nude photos, which has been growing over the past few years, exploded when J-pop singer 'hitomi' published a pregnant nude picture with her new album last June.

The picture was displayed on large billboards over busy streets in Tokyo and the related photo book became a bestseller, selling more than 10,000 copies in its first week of publication, according to local media.

"The special feeling of waiting for motherhood helps alleviate the fear of nudity. And with more women becoming pregnant at a late age, for them this is an experience that will never happen again," said Yuko Ishizaki, an assistant professor at Japan Women's University.

Mums-to-be pay around 35,000 yen ($368.2) for a studio photo shoot, which takes less than two hours in "Ixchel."

"Before this boom, women didn't know where to go to take these kinds of pictures even though they wanted to. Because of media attention, they easily found our studio," said Natsuko Takada, the owner of photo studio "Ixchel."

"When I opened my studio for maternity photos last year we had less than 10 customers a month but last month we had more than 70 customers," said Takada.