Over 10,000 girls under the age of consent – some as young as twelve – have been given contraceptive implants on the NHS in the past two years.
Parents are often not informed about the devices.
Critics said the official figures showed parents were being undermined, and that a “casual attitude” to underage sex is exposing children to danger.
Statistics from NHS Digital show 10,593 children under 15 were given the implants between 2015 and 2017, including 39 girls aged twelve or under.
The devices, which can be implanted by a nurse, produce a hormone which prevents the release of an egg for up to three years.
In the UK, having sex with a child under 13 is automatically treated as rape. For 13 to 15-year-old victims where absence of consent cannot be proven, the offence is sexual activity with a child, which carries a lower sentence.
Sir Roger Gale, Conservative MP for North Thanet, where the implants are offered in schools, said his chief concern was a lack of parental consent.
He said, “parents have a right and a duty to know what is being done to and for their children”, adding that the situation was “like a doctor saying I know your child is taking drugs but I’m not going to tell you so you can’t do anything about it”.
Mark Bhagwandin, of the pro-life charity Life, called for an end to the “persistent undermining of parental responsibility”.
The Family Education Trust’s Norman Wells also expressed his concerns: “The NHS’s short-sighted policy in this area is giving girls a licence to engage in illegal sexual activity.
“The Government needs to wake up to the fact that a casual attitude towards underage sex is exposing children and young people to the risk of sexual exploitation.’
But pro-abortion group FPA backed the scheme, claiming: “Taking away access to contraception won’t prevent young people from having sex”.