"She asked the neighbour to look after them and then she went to the shops and she never saw them again," she said.
It was not until 1987 that Martin's mother learned Williams died in Christchurch four years after leaving, after getting toxaemia - or blood poising - from a backstreet abortion.
They later found her unmarked grave.
"My mother always thought that Beverley never came back because she never cared about or loved her. But Beverley was dead," she said.
"She's a woman that found herself in a circumstance that was difficult and she paid a price, for a decision she had to make, that she shouldn't have had to pay."
Williams' sister had died a year later in the same circumstances, Martin said.
"Beverley has been invisible and she should never be forgotten."
Martin said it was important to tell the story as part of the current debate into abortion reform.
"Under the current law she would have been able to go see three doctors and go get something," she said.
"But women have had to seek a termination because of circumstances in their lives since time immemorial and we need to make sure they're safe when they do it."
Martin said she had asked her mother's permission before Thursday's debate.
"My mother made a comment I had never heard her make before: if Beverley had been able to, without stigma and without shame, go and get an abortion, maybe that six-year-old girl would have still had a mother," she said.
NZ First had given her their slot to speak personally, but the situation had changed.
"I'm not frustrated. That's just my reality. I had thought very carefully about the speech I was going to give," she said.
"Things just changed on that Tuesday morning … I don't begrudge them."
The bill passed its first reading 94 votes to 23 and will now be considered by a Select Committee.