A majority of women in mid-western Nepal are banished from their homes multiple times a year during their period, according to a recent study. Sent to "menstruation huts" – usually in the form of tiny sheds or animal shelters – women are often isolated, cold and vulnerable to attacks during their monthly ritual of displacement.

Associated with Hinduism, the practice is called chhaupadi and is based on the belief that women are "impure" when they're on their periods, and therefore need to be avoided. Adherents believe that banishing them every month is necessary to avoid misfortune. 

The belief changes how girls are allowed to live during their periods, including forbidding them from eating certain foods, who they can touch and which places they can enter. The monthly exile can be dangerous, and girls often deal with hunger, illness and in some cases, death. In January, a woman and her two sons were found dead after suffocating in a menstruation hut in Nepal. 

In cases where huts are damaged, the women are essentially rendered homeless. "If they did not have access to a chhau hut, or if it had been damaged or destroyed, we heard anecdotal evidence that women were often forced to sleep outside, open to the elements, or with animals," wrote the paper's authors in Sexual and Reproductive Health Matters.

Though chhaupadi was criminalized in 2005, the practice is still widespread in Nepal, with researchers finding that 77 percent of girls surveyed were still living in these huts while on their periods.

In April, researchers from the University of Bath conducted focus groups with adolescents and women aged 25-45, along with a survey of 400 girls between the ages of 14-19 in mid-western Nepal. Sixty percent of the girls surveyed knew it was illegal, yet they were just as likely to practice chhaupadi as those who didn't know. 

Many of the girls learn the practice from the women before them. Tradition is typically upheld by "elders within their family and community," such as mothers, grandmothers and other senior women who also practiced chhaupadi, the study found. 

While activists say criminalization has been an important step, more is needed to affect real change. "The Nepali government and NGOs need to think about other methods that can be employed to address the issue of chhaupadi – community based action or school-centered interventions," suggested Dr. Jennifer Thomson, a researcher involved in the study. 

The study's authors also suggest expanding the scope of the issue. While many view menstruation as a gender issue, the paper suggests reframing it as a human right. Menstruation is largely viewed within international development as an issue for the WASH (water, sanitation and hygiene) sector, but there's arguments to be made, "especially around girls' safety, security and dignity" in relationship to menstruation that human rights organizations need to pay attention to, said Thomson. 

"This is about changing deeply ingrained cultural practices and behaviors, and while changing the law is important, this study shows it's going to take much more than that. These are practices that have gone on for generations and generations," wrote the paper.