Two men taking a stroll through Île de la Visitation Park dived into the Rivière des Prairies and pulled the 28-year-old mother and her children out of the water.
But on Monday, the 4-year-old died of his injuries, and on Wednesday afternoon, the mother perished at Jean Talon Hospital.
The 2-month-old has survived and has been returned to his father's care.
Montreal police have closed the case on what they had been investigating as a murder-suicide. Police never did get the opportunity to question the woman, so her motives will never be known.
But the possibility that postpartum psychosis might have been a contributing factor looms large.
And the tragedy also raises questions about whether Quebec's health-care system has sufficient resources in place to screen for or treat this rare condition, in which a mother loses touch with reality shortly following childbirth and is at high risk of harming herself and her children.
Dr. Louis Bérard, a psychiatrist at the Institut Philippe Pinel, noted postpartum psychosis affects one in 1,000 women after childbirth.
He stressed this mental disorder should not be confused with the more common form of postpartum depression, which occurs in about one in 10 women.
"Some women suffering from postpartum psychosis do not suffer from depression, have not suffered from depression and will never suffer from it," Bérard said.
"In some women, the psychosis might be the first bout of schizophrenia, for instance. It may be caused by drug use."
Bérard also cautioned that it does not necessarily follow that a woman suffering from postpartum depression will develop psychosis, although the former condition is still serious and must be treated.
"The best way to prevent such tragedies is to make sure we have a good system of support for new moms. Most women are not alone, and if a husband, parents or any wellintentioned relative or acquaintance thinks that there is something wrong, they certainly may help the person go to the hospital or ask for the emergency services to intervene.
"There are adequate resources, I believe," he added.
In Quebec, CLSC clinics organize pre-natal classes that address topics like the baby blues ? which affects up to six in 10 women following childbirth but is not lingering ? as well as the more serious condition of postpartum depression.
Within days of the birth of a child, a CLSC nurse will pay a visit to the mother to weigh the baby and to counsel the mother on breastfeeding, among other issues.
The CLSC nurse will also ask questions about the mother's mental state, and if she is exhibiting depressive or delusional symptoms, she will be referred to a psychologist or psychiatrist.
Two months after the birth of the child - when postpartum depression and the much rarer disorder of psychosis are more likely to occur - it is the routine practice of CLSC nurses to phone the mother to assess her mental state.
Diane Felipe, a nurse who manages the family, child and youth program at the CLSC René Cassin in Côte St. Luc, recalled an incident in which a colleague of hers phoned a mother and discovered that she was delusional.
"In that case what the nurse did was call the woman's husband and she advised him to take his wife to the emergency department of a hospital right away," Felipe said.
Bérard said that although postpartum psychosis is very dangerous, if a woman is brought to hospital she can be stabilized fairly quickly.
In addition to the CLSCs, most Montreal hospitals provide mental health therapy to women during pregnancy as well as six months after birth.
Dr. Barbara Hayton, director of perinatal mental health services at the Jewish General Hospital, said that symptoms of depression are usually present even during pregnancy.
An obstetrician will often refer a depressed patient to Hayton during her pregnancy or after the birth.
The patient will then be treated with a combination of psychotherapy and anti-depressants.
"It is known that postpartum depression can affect the children and their development," Hayton said. "So if you can treat the mother, that baby has a chance of developing normally.
"We also know that postpartum depression affects the fathers. When women are depressed during the postpartum period, there's a 25 per cent incidence of fathers having postpartum depression. So then you're dealing with two depressed parents.
"So identifying the woman and treating her can hopefully have a beneficial effect for the entire family," she added.
Still, Hayton bemoaned the lack of mental-health services, not just for young mothers in the postpartum period, but for all Quebecers suffering from psychiatric illness.
aderfel@montrealgazette.com