Girls as young as 10 are being prescribed the contraceptive pill, it has been revealed.
Doctors can prescribe the pill to under 16s
Researchers at the University of Aberdeen found 23 girls under 13 had been given the Pill - two were under 10 years old.
They looked at data from GP practices and family planning clinics in Scotland.
The study in Archives of Disease in Childhood prompted claims that doctors may be breaking the law.
The British Medical Association and the General Medical Council tell doctors girls of any age can be given the pill as long as they are thought to be mature enough.
However, in Scotland, having sex with a child aged under 13 is classified as statutory rape.
And if girls under 13 are prescribed the Pill, doctors are expected to report it to the police or a social worker.
But it is not known whether this happened in the 23 cases in the study by Professor Peter Helms and Dr James McLay.
A total of 1,376 girls under 16 were prescribed the oral contraceptive.
Dr McLay said: "One of the worries we have is that people who are under 13 on the oral contraceptive should be reported to social workers because they are being subjected to rape."
But the researchers said that the overall rate of oral contraceptive use among girls aged 10 to 16 remained low, despite the medical and social concerns about the sexual health of teenagers.
They pointed out that the UK has the highest rate of teenage pregnancy in Western Europe.
A spokesman from the BMA said that if the girl was determined to be sexually active then, given the risks of pregnancy and abortion, it might be the doctor considers giving her the Pill "the lesser of other evils".
A spokeswoman from the Family Planning Association said: "This is highly unusual and there may well have been particular reasons why these girls were prescribed the Pill."
This could include menstrual problems such as heavy periods, she said, and pointed out that girls can begin having periods at as young as eight.
"GPs clearly have a responsibility to prescribe sensibly and they do.
"Ultimately, they have to make decisions on a case by case basis."
But the Scottish National Party's health spokeswoman Shona Robison said the practice should be ceased immediately.
She said: "I think there are huge ethical, moral and legal issues involved here, given that it is essentially statutory rape for anyone to be having sex with girls that age."
A Scottish Executive spokeswoman said: ¿Prescription of the pill is a matter for individual doctors, based on clinical judgment. Prescription data does not identify the reason why any treatment is prescribed for a particular patient (regardless of age).
¿It is important to note that the contraceptive pill can be prescribed for reasons other than contraception, for example, hormonal control generally, period irregularities, menstrual disorders including painful periods, hormonal regulation in infertility treatment and acne."
The national charity LIFE said that if it heard of any doctor, school nurse or family planning clinic giving the Pill to very young girls it would immediately report them to the police.
A spokesman said: "Giving the Pill to ten-year- olds (without, of course, parents' knowledge) may seem to be a sensible 'quick fix' but in reality will make very immature children yet more vulnerable to sexual exploitation and encourage self-destructive behaviour."
Jan Barlow, Chief Executive of Brook, the sexual health charity for young people, said: "The law is very clear and young people should be reassured that they do have a right to confidential sexual health advice.
"If young people don't feel they can trust health professionals to treat their enquiries confidentially, there is a real risk that they will put themselves at risk of unplanned pregnancies or sexually transmitted infections."