When Mick-Sophie Anne started showing signs of puberty at age 10, her mother took a hot stone and firmly pushed it down on her daughter's breasts in an attempt to flatten her chest.

At dusk, in a small, dark kitchen out of sight of the neighbours, Priscille Dissake would heat the fist-sized stone on a charcoal fire and press Mick-Sophie's breasts every evening for two months. Dissake's sister would help by pinning the girl down on the cold, hard floor to stop her running away.

New government research shows that 'breast ironing,' as the harmful custom is known, has seen a 50 percent decline since it was first accidentally uncovered during a 2005 survey by the German Technical Cooperation Agency (GTZ) on rape and incest in Cameroon.

A successful nationwide awareness campaign in schools, churches and across media outlets has drawn attention to the harmful physical and psychological consequences. However, despite the work of children's rights activists, 1.3 million girls are still victims of the brutal practice today.

Mothers do it to try to protect their daughters from premarital sex, early pregnancy and rape.

"Mick-Sophie started developing breasts very early and she was becoming attractive. I wanted to guard her childhood and protect her from men," said Dissake, 46, speaking in the same kitchen where she had applied the burning stone to her daughter's body more than 20 years ago.

"I had Mick-Sophie when I was just 14, but her father was never around. It was a really hard time for me and I didn't want the same thing to happen to my only girl."

Dissake's efforts were in vain. By her own account and that of her mother, Mick-Sophie was raped by an uncle at age 13. A year later, she started having sex with a classmate. At 16, she gave birth to her first child. The baby was six weeks premature and died a few hours later.

INTERNATIONAL PRACTICE

Although Cameroon is the only country where thorough research has been carried out on breast ironing, rights groups believe the practice is widespread across the region and among the West African diaspora, including in Western countries with stringent child-protection laws.

"We Africans take our culture everywhere we go, so I am sure it is happening in Britain and America too," said Margaret Nyuydzewira, who was born in Bamenda in northwest Cameroon, where breast ironing is common.

Nyuydzewira co-founded CAWOGIDO, an organization that campaigns against breast ironing in Britain, where 9,600 Cameroonians live according to the last census in 2011.

She said a couple of cases of breast ironing had been reported in Birmingham and London over the past few years, but the prevalence is likely to be far higher.

"People within the practising community know that it is happening, but it is hidden and done at home. It's like FGM (female genital mutilation) - you know it's going on, but you will never see anyone doing it," she said.

"It's happening in Nigeria, in Burkina Faso, in Chad, in CAR (Central African Republic) and other countries in the region too. They just call it a different name in their local language," she said.

TEEN PREGNANCIES

Breast ironing is a relatively new practice that only began to gain popularity around the 1930s when Cameroonians started moving from their rural homelands to cities in search of jobs, anthropologist and aid worker Flavien Ndonko said.

"In these cities, there was less social control and norms as different cultures mixed freely. Soon, as girls started going to school and finding opportunities outside the household there was more chance of premarital sex," said Ndonko, who works for GIZ, the German state-owned development agency.

"Meanwhile better hygiene, nutrition and healthcare means that girls are shooting (growing) breasts much earlier, making them look older than they are. The average age of breast growth for girls in Cameroon has dropped from around 13-1/2 years old to just under 12 in the last 100 years."

As Cameroon remains a deeply conservative nation where getting pregnant outside marriage is frowned upon and abortion is highly restricted, mothers use breast ironing as an unorthodox form of contraception to ensure their daughters don't fall pregnant and drop out of school.

The most recent social and demographic health survey conducted in Cameroon in 2011 showed that 20 to 30 percent of Cameroonian girls get pregnant before the age of 16 and a third abandon their studies.

These figures could explain an unusual aspect of this practice. The new research found that around 16 percent of girls - especially in the Far North region where there is a tradition of child marriage - try to flatten their own breasts with hot stones or pestles so they can delay their sexual maturity and continue going to school.

MEDICAL PROBLEMS

Despite what Dissake and other mothers say about their good intentions towards their daughters, they unknowingly risked leaving them with severe physical and psychological problems, health workers say.

The government survey, funded by GIZ, found that a number of respondents had a range of medical problems, including breast cancer.

"We found 20-year-old girls who had already been diagnosed with breast cancer," Ndonko said. "We don't know if there is a direct link between the practice and cancer, but it certainly raises suspicions."

Thirty-two percent of respondents complained about pain in the breasts and 17 percent spoke of cysts and abscesses. Thirteen percent suffered heaviness of the breasts and eight percent permanent deformation, according to the study

The lasting physical scarring and damage can have a long-term psychological impact too, it concluded.

"As the girls sexually mature, they feel they cannot show their breasts to their boyfriends or husbands," Ndonko said. "Some girls felt so ashamed they were having sex without fully removing their clothes so they can hide their breasts."

Ndonko coined the term "breast ironing" to try to convey the pain and trauma adolescent girls feel. But both Ndonko and Nyuydzewira believe mothers should not be criminalized but should be informed of the consequences of the practice.

"We should educate them first, and then we should punish them if they continue," said Nyuydzewira.

Punishing mothers could prove difficult. In many cases, the girls go along with it willingly, believing their mothers are protecting them. But for Nyuydzewira, even if there is not a clear villain, there is a clear victim.

"The responsibility has to lie with the mother because the girls are still children and they are agreeing to do it out of fear and respect," she said.

In the gloom of her kitchen, Dissake was overwhelmed with guilt. "I meant well. I ask for forgiveness for what I thought was wisdom but turned out to be ignorance," she said.

"Breast ironing hurts more than childbirth," said Mick-Sophie Anne. "I forgive my mother, but I'll never forget it."