( CNN ) -- Every morning before school , nine-year-old Terisia Techu would undergo a painful procedure . Her mother would take a burning hot pestle straight out of a fire and use it to press her breasts . With tears in her eyes as she recalls what it was like , Terisia tells CNN that one day the pestle was so hot , it burned her , leaving a mark . Now 18 , she is still traumatized . Her mother , Grace , denies the incident . But she proudly demonstrates the method she used on her daughter for several weeks , saying the goal was to make her less desirable to boys -- and stave off pregnancy . A study found that one in four girls in Cameroon have been affected by the practice . The U.S. State Department , in its 2010 human rights report on Cameroon , cited news reports and said breast ironing `` victimized numerous girls in the country '' and in some cases `` resulted in burns , deformities , and psychological problems . '' There are more than 200 ethnic groups in Cameroon with different norms and customs . Breast ironing is practiced by all of them . Some mothers use hot stones or coconut shells to flatten their daughters ' breasts . Doctors believe improved diets have resulted in young Cameroonian girls going through puberty early . Many of them are also becoming pregnant early . Terisia became pregnant at 15 . Her child died at birth . She told CNN that breast ironing does n't work . She hates the practice and wishes her mother had instead talked to her about sex and preventing pregnancy . Grace Techu argues that if it were n't for the breast ironing , Terisia would have become pregnant at an even younger age . Techu has four daughters , and she used the procedure on the first two . The third avoided it because her breasts are growing at an acceptable rate , Techu says , and the fourth girl is still too young . Mothers who want their children to finish school before becoming parents have resorted to this drastic measure , and many see nothing wrong with it . In 2006 , a German nongovernmental organization exposed the practice , which at the time was done mainly in secret . Now , charities have embarked on campaigns to educate mothers in Cameroon that sex education -- not breast ironing -- is the solution to ending teenage pregnancy . Dr Sinou Tchana , a gynecologist in Cameroon , has seen breast glands that were destroyed . She also saw one case of cancer , though she says it could n't be established whether the ironing caused or only exacerbated the cancer . `` One mother came with secondary burns because the stone she was using to do this breast ironing burned her , '' Tchana says . One of Tchana 's patients is a 23-year-old whose scars are still painful 14 years after her breasts were ironed . She has joined the effort to confront mothers about the effects of their actions . The challenge for all those trying to stop the practice is reaching parents like Techu in villages before a ritual that they say is motivated by love shatters more lives . CNN 's Josh Levs contributed to this report .
1 in 4 girls in Cameroon are affected , a study found . All of the more than 200 ethnic groups practice the practice . The US State Department assails the practice . Charities want to show girls in Cameroon that their education , not the law , is the issue .