For the first time in 32 years, pregnant women can bathe in an onsen this summer without worrying about harming themselves or their unborn baby, according to a new government guideline.

Under the new guideline adopted in July, the Environment Ministry removed pregnant women from a list of those unfit for soaking in hot springs after failing to find scientific evidence that a good soak endangers pregnancy.

The previous guideline had been in effect since in 1982.

The list of people unfit for onsen still includes cancer patients and those with serious heart disease, and the hot spring law states that hot springs must prominently display the warnings.

A panel under the ministry studied medical papers from Japan and overseas but could not find anything on onsen causing premature birth, miscarriages or other pregnancy risks, the officials said.

They don't even know exactly why pregnant women were put on the list in the first place.

"It could be out of concern that the floor of a bathhouse is slippery, and pregnant women tend to get dizzy easily," one official said.

The new guideline, however, adds stress-related problems, such as depression and sleeping disorders, to the list of maladies that could be alleviated by a good soak.

Given the changes, the city of Beppu, Oita Prefecture, which boasts the most hot springs in Japan, began observing the new guidelines on Thursday, a municipal official said.

"We welcome the revision of the guideline. Now, more people can enjoy bathing without worry," the official said.