"New mothers with severe mental illness are often treated and supported in adult acute mental health units separated from their babies and families," Mr Ryall said.
"Mothers will now get the support of the new specialised maternal mental health services with their babies beside them."
Medical experts, women's groups and post-natal support groups have welcomed the plan to fill this gap in maternal, infant and mental health services.
The Ministry of Health, in a report on gaps in maternal mental health services, estimated last year, based on recommendations used in Britain, that the North Island might need between 13 and 26 inpatient beds.
Only Christchurch has a mental health mother-and-baby unit, a five-bed facility that serves all of the South Island. The closest Auckland gets to this is two community respite beds mainly for the women of Counties Manukau.
In Auckland, if a woman becomes seriously mentally unwell after birth and needs to be admitted to a psychiatric hospital, she has to be separated from her baby, for the safety of the child.
Part of the reason for this goes back to a tragedy in the early 1970s. The baby of a patient at the psychiatric ward at the old Auckland Hospital was fatally injured by another patient.
The ministry report says disrupting the mother-baby relationship, in the absence of other nurturing primary caregiving relationships, can result in delayed social and emotional development and significant behavioural problems for the infant.
In turn this can lead to failure at school, mental illness, chronic physical ill-health, unemployment and criminal offending that may persist into adulthood.
Dr Cathy Hapgood, formerly a psychiatrist at the Waitemata District Health Board's outpatient maternal mental health service, said sometimes it was imperative to admit a new mother to an acute mental health unit even though she had to be separated from her baby.
"Necessarily we try to keep the admission very short, because they want to be at home with their baby and generally the family want them at home with the baby.
"Somebody else has had to take care of the baby. It's very disruptive and difficult for everybody."
"It can potentially set up a disrupted attachment. The mother can lose her confidence very much with the baby by somebody else looking after the baby while they're in hospital," she said.
"Sometimes they get discharged quite quickly and then they come home and they have to step up and that can be very difficult when they are not fully recovered."
The ministry says it is estimated that maternal psychiatric disorders occur during pregnancy or in the months following birth in at least 15 per cent of pregnancies. The illnesses include depression, anxiety disorders, bipolar disorder and post-natal psychosis. Post-natal depression is the commonest post-birth mental disorder and, during pregnancy, between 7 and 26 per cent of women meet the criteria for major or minor depression.
Dr Hapgood said post-natal psychosis could be severe.
"Those are one of the groups of women that may well benefit from admission to a mother-and-baby unit. Puerperal [post-natal] psychosis can put women at risk of psychosis at other times. Some might have only one episode. Some will go on to experience psychosis after the baby. A small number of them may go on to develop bipolar disorder."
She said mother-and-baby units, which had been established in a number of urban areas in Australia, were different from other mental health facilities.
"It might be a little bit more domestic. Because mothers come in with the baby, usually you have a nursery area, an area where the mothers can be with their babies, where they can wash clothes and make up bottles. It can sometimes contain people who are quite unwell but the focus is on mother and baby, the mother being treated with the baby there."
Dr Hapgood was a subcommittee member of the Perinatal and Maternal Mortality Committee, chaired by Auckland University professor of obstetrics and gynaecology Cindy Farquhar, which has repeatedly called for a mother-and-baby unit in the North Island.
The committee, which last year reported suicide was the leading cause of maternal mortality, recommended that such a unit be created "in addition to an improvement in the currently stretched resource".
Professor Farquhar said having to separate severely unwell mothers from their babies compounded their problems - "because they want to be a good mother but they have got to separate so they can't continue breast feeding and can't continue looking after the baby.
"We are looking forward to a comprehensive service - support in the community as well as looking after women who are acutely unwell and need to be hospitalised with their babies."
Dr Hapgood said another benefit would be to help address the stigma and anxiety women face when they become mentally unwell after the birth of their baby.
"Having a mother-and-baby unit would really make a statement that these things happen sometimes, but we have a place where we can treat you."
What are post-natal blues?
Affects more than half of mothers, usually from three or four days after birth. Typically lasts no more than a few days. The woman will feel more emotional and vulnerable than usual and may cry without reason.
What is post-natal depression?
Between 10 and 15 per cent of mothers suffer depression following the birth of their baby.
Can occur from soon after the birth to up to two years later.
Symptoms can include low mood, insomnia, tearfulness, tiredness, anxiety, negative thoughts, and problems with concentration.
Usually resolves on its own, but treatment can reduce severity and duration of symptoms.
What is post-natal psychosis?
Also called puerperal psychosis and is usually a form of bipolar disorder. The serious and potentially life-threatening mental illness which affects up to one mother in 500 following birth requires urgent treatment.
Typically develops within four weeks of birth but can occur later and women can have relapses.
Symptoms can include delusions, hallucinations, nightmares, insomnia, paranoia, suicidal thoughts, fluctuating mood and thoughts of harming the baby.
What help is available?
GPs
District health board maternal mental health services
•Postnatal Distress Support Network Trust, (09) 836 6967, postnataldistress.org.nz
•Post Natal Psychosis Support Group, contact via healthpoint.co.nz
•Postnatal Depression Family/Whanau NZ Trust for information and directory, mothersmatter.co.nz
