Young women from the age of 15 are being sent mobile phone text reminders to take the contraceptive pill.
The project is for women and girls who are already on the pill
South Birmingham Primary Care Trust is paying £5,000 for daily messages to 300 women aged from 15 and 25, for seven pill cycles each.
If necessary the messages are sent in code to women who have registered, says the trust.
The anti-abortion charity Life condemned the idea and said it would lead to increased promiscuity.
The health trust said only young women already taking the pill under the supervision of their GPs were being targeted.
In a statement it said: "It is a scheme to promote correct use of prescribed medication, rather than to promote the use of contraception or to encourage sexual intercourse."
Knot in handkerchief
Chris Spencer-Jones, director of public health for South Birmingham Primary Care Trust, said: "It is a modern version of the knot in the handkerchief.
"We hope this scheme will reduce the number of unintended pregnancies in the younger age groups who have adopted texting as a way of life."
John Scarisbrick, chairman of Life, which is based in Royal Leamington Spa, Warwickshire, said the idea was disgraceful.
"It will lead to increased promiscuity, more sexually-transmitted diseases and ultimately more unhappiness.
"My message to them is - mind your own business," he said.