Abort67 volunteers Pauline Peachy and Kathryn Attwood were outside the Wistons abortion clinic when a young woman got out of a taxi and entered the clinic.
A little while later, the woman emerged from the clinic, having not taken the pill, and came to hear what they had to say.
"She took some leaflets, but when I showed her the little feet pin she started to cry. We talked together for a while. We asked her what help she needed to keep the baby, said that whatever it was, we could provide it - God has never let us down!," explains Peachy.
She and Attwood then went with the woman to a nearby cafÃ© where they could talk more about her options.
"She was afraid. Her husband was afraid," Peachy said. "She was a Catholic who believed in God. She wanted to have an early abortion because she thought it wasn't really a baby yet."
Attwood added: "After our conversation with her she was adamant she would keep the baby no matter what anybody said.
"I think that baby was saved through a combination of factors. Firstly, the Holy Spirit softening her heart through prayer. Secondly, our obedience to God to stand outside the clinic and openly share with her the reality of abortion."
Abort67 is running a two-day pro-life training conference called the Clarkson Academy this September.
The conference, supported by Christian Concern, is taking place in central London from 5 to 7 September and will train more volunteers in educating people about what abortion involves.
"Abortion laws won't change unless the truth about abortion is exposed," said Christian Concern.