text: It is the first private clinic to offer early medical abortions to women in Northern Ireland under strict legal controls.
  A former leader of the Progressive Unionist Party, Ms Purvis has been director of the clinic since it was launched in 2012.
  Ms Purvis, who will step down on 24 April, said it was "time to move on".
  She will take on a new role on the clinic's Northern Ireland advisory board.
  Last November, anti-abortion protester Bernadette Smyth, who leads the Precious Life group, was convicted of harassing Ms Purvis at the Marie Stopes office in Belfast city centre.
  Ms Purvis told the BBC that had had no influence on her decision to step down.
  "I think the clinic's well established here now, we're providing services more and more every year and I'm delighted to be remaining on the advisory board for the clinic.
  "But I feel it's time to move on and I think it's time for Marie Stopes to get someone else in to manage the clinic and take it to new places," she said.
  "At times it was difficult, particularly last year with the court case and the harassment, but I put that behind me and have concentrated on delivering services for women in Ireland both north and south.
  "I think I've achieved a significant historical change in the perception of abortion in Northern Ireland from where the usual narrative was that abortion was illegal in Northern Ireland to now one where people understand that abortion is legal under certain circumstances.
  "I think we've challenged the myths and stereotypes that are presented by those who are opposed to a woman's right to chose."
  Genevieve Edwards, director of policy for Marie Stopes UK, said: "We were so lucky to have Dawn and wish her every success in whatever she chooses to do.
  "The support for the clinic since it opened in very challenging circumstances has been heartening and a source of great comfort and pride for our staff and volunteers.
  "We are now actively recruiting for Dawn's successor to lead us into the next phase of the clinic's journey."
target: Dawn Purvis is to step down as programme director of Northern Ireland's Marie Stopes clinic.