"Women in our society are experiencing an enormous amount of despair, often coupled with depression and anxiety," said Dr Simone Honikman, director of the University of Cape Town's Perinatal Mental Health Project.
"And the time around pregnancy and the first year of a child's life represents an extremely stressful time for women."
The summit, convened in Cape Town by Western Cape Social Development Minister Patricia de Lille, drew about 80 representatives of non-government organisations, churches, academics and teachers.
It followed a string of reports of abandoned babies in the Cape Town area, and several gruesome cases of mothers killing their children.
Honikman said global evidence was that people who lived in poverty were more likely to experience mental illness.
Maternal depression was "extremely prevalent" in South Africa.
In developed countries the figure was 10 to 15%; studies in South Africa had shown that during pregnancy about 40% of women were depressed.
In the first year after pregnancy, between a third and half of South African women experienced depression.
"One in three women is a terrifying epidemic," she said.
"We need to remember that depression affects not only the thoughts of people, but it affects how they are able to organise their lives, make decisions, weigh up options."
Honikman said the mental illness that could result in abandonment, abuse and even infanticide should be addressed with compassion and treatment, rather than a punitive approach.
She said she did not think tougher law enforcement would help.
"We need to recognise that these are women in trouble, and who need care and support."
She said antenatal checks offered the ideal opportunity for psychiatric screening to identify women who were at risk or suffering from emotional distress.
They could then be referred to counselling and social services.
"That's what I believe we should do if we are going to address this problem (abandonment) in a systematic way," she said.
Honikman said her project had screened some 8 500 women since it started in 2002.
The screening had been done in obstetric or maternity facilities, and women had where necessary been referred to quality counselling on the same site.
'Can't afford to ignore mental health'
"That's been very effective," she said.
"I think it's absolutely vital. There are other places in the world where mental healthcare is integrated routinely into obstetric care, and there's no reason why we shouldn't be doing this, especially when we've got a much, much higher prevalence.
"I think we're ethically obliged to address this problem. I don't think we can afford to ignore mental health because it's non-biological."
Penny Whitaker, of Cape Town Child Welfare, told the summit that there had been no sudden spike in the number of abandoned children in the city, but rather a steady rise.
However the way children were being abandoned suggested that their mothers were in increasingly desperate circumstances.
De Lille said that just as one could not justify abandoning or killing a young child, one could not ignore the responsibility of the father.
Fathers often did not pay maintenance.
"As part of our solution we must begin to say a child must be looked after by both parents," she said.
Her views were echoed by Premier Helen Zille, who said too many people did not link the act of sex to the creation of a new life.
"So many men in our society make a baby and walk away from it, and don't feel guilty about doing so," she said.
She said the one-off payment for fathering a child out of wedlock, customary in some traditional communities, was no compensation for the absence of a father in that child's life.