Female drug users worldwide are far less likely than their male counterparts to undergo treatment due to discrimination against mothers and pregnant women and the cost of childcare, transport and treatment, the U.N. drugs body said on Friday.

Women with drug problems are heavily stigmatized and find it difficult to leave their homes or families for treatment, according to the United Nations Office on Drugs and Crime's (UNODC) annual World Drug Report.

Punitive attitudes toward mothers and pregnant women mean many fear losing custody of their children as a condition of treatment, and this prevents them from seeking care, the UNODC said.

"Women in particular appear to face barriers to treatment," UNODC Executive Director Yury Fedotov said in a statement.

"While one out of three drug users globally is a woman, only one out of five drug users in treatment is a woman."

Women are three times less likely than men to use cannabis, cocaine or amphetamines but more likely to misuse prescription drugs, according to the UNODC.

Yet women who use drugs are at higher risk than male users of developing more severe health problems, the report said.

The U.N. body said there was a lack of information about women with drug problems and few services were designed for women, especially in poorer countries.

Women with children who wish to join outpatient treatment programs often find it difficult to pay for child-care, transport or treatment itself, according to the UNODC.

Many women with drug use disorders tend to come from families where one or more family members is also drug dependent, and identify relationship problems as a reason for their use of drugs, the report said.

While men may be referred for treatment by their family, an employer or the criminal justice system, female drug users are more likely to be identified and referred by social services or health workers when seeking help for other problems, including mental health issues, the UNODC said.

The report said drug use prevalence remains stable worldwide. An estimated 246 million people - around five percent of those aged 15 to 64 - used an illicit drug in 2013, and some 27 million people have drug problems, according to the UNODC.