A controversial scheme allowing girls as young as 13 to obtain the contraceptive pill from pharmacies is being piloted on the Isle of Wight.
Teenagers who approach a chemist for the morning-after pill will also be able to get a month's supply of the contraceptive pill without seeing a doctor or informing their parents.
Isle of Wight Primary Care Trust said it would reduce unwanted pregnancies.
However, church and campaign groups have called the move "irresponsible".
Ten of the Isle of Wight's 30 pharmacies will be able to provide a month's supply of the pill to a teenager without the need for a prescription.
After that month is up, girls must make an appointment with their GP or sexual health nurse in order to get any additional supplies.
Jennifer Smith, from the Isle of Wight NHS Primary Care Trust, said: "They are already sexually active, we haven't encouraged them to be sexually active.
"I would suggest that what we're doing is being entirely responsible by providing [contraception to] these most vulnerable women, for whom, for the most part, pregnancy is not a good outcome.
"We are linking them with people most able to support them in further decision-making and appropriate behaviour in the future."
The NHS trust said the service was not focused on younger teenagers, but it has still attracted criticism.
The Reverend Anthony Glaysher, from the Catholic diocese of Portsmouth, said it "fundamentally attacked the family".
The Conservative MP for the Isle of Wight, Andrew Turner, asked: "How can adults bring up their children if their children can go into a shop, more or less, and be handed over something which is so significant?
"I will be making my concern clear to the people who run the health service and they've got to understand that many people feel the same."
The latest figures for teenage pregnancy on the Isle of Wight show a year-on-year increase - after a gradual decrease in the preceding years - with 96 girls under the age of 18 becoming pregnant in 2008.
Labour's target of halving the overall number of teenage pregnancies by 2010 is widely expected to be missed, but some fear the issue is not high enough on the coalition government's agenda.
Hilary Pannack, chief executive of charity Straight Talking, said: "We need to be very cautious about this, I don't think it is going to be the answer to teenage pregnancies.
"We need to have a very practical and sensible approach because we can't lock our children up in the house, or say to them 'don't do it', we have to be realistic."
Antonia Tully, from the Safe at School campaign group, said: "Teenagers need parenting not pills. Typically this sort of situation is removing parents out of the scene, I think this is very risky."
The group said it was the prerogative of parents to discuss contraception with their children when appropriate.
Prof Roger Ingham, a member of a soon-to-be-defunct quango designed to try to achieve Labour's ambition, the Teenage Pregnancy Independent Advisory Group, told the BBC: "In each local area there's been a teenage pregnancy co-ordinator and associated staff that have kept the issue on the boil.
"Now, a lot of these posts are going to go with the cuts, with the lack of national targets, and I think a lot of the expertise we've built up over the last 10 years will gradually fade away and I think that's a great shame."