A screening program at the Royal Women's Hospital in Randwick flagged Emily as being at high risk of developing perinatal depression and anxiety when she was in the early stages of her second pregnancy.

The Sydney professional had a history of mental health conditions, her pregnancy was unplanned and her mother had experienced severe postnatal depression and psychosis.

Emily also carried a foreboding memory of her husband coming home one afternoon when their daughter was six months old. He said he wanted to kill himself, that he had not been going to work and instead had gambled away their baby bonus.

"I took that trauma into my second pregnancy."

Emily's experience is not uncommon. One in five women during perinatal period (the weeks before and after the birth of their baby) will experience mental health problems.

Now, new national perinatal guidelines recommend every woman be screened for mental health issues during pregnancy and after their baby is born as part of routine maternity and postnatal care.

A growing body of research has exposed the critical effects of maternal depression, anxiety and other mental illnesses on both the mother and baby.

Most cases cases of perinatal mental health conditions go undetected, with fewer than 20 per cent coming to the attention of health care practitioners. Even fewer will get treatment, according to research that underpinned the guidelines.

The perinatal mental health service at the Royal Women's Hospital rallied around Emily.

She had regular sessions with a psychologist who visited her at home once her son was born. The service continually monitored her emotional as well as physical maternity care, and helped manage her anxiety medication.

"For me it was a huge relief," Emily said. "Because things did deteriorate."

Emily's husband had started gambling again. He lost his job and her close friend died suddenly when she was about 36 weeks.

She was sleep deprived and struggling to pierce through intrusive thoughts that fixated on her husband's gambling, her first traumatic birth and anxieties about leaving work and financial instability.

"Once things got really bad I felt like I was just holding onto reality," Emily said.

"The fact that I had so much support probably saved my life. I'd never before had that continuity of care."

"That I was picked up early made all the difference ... that level of care should be available to all pregnant women, wherever they go," she said.

The perinatal guidelines commissioned by the federal government include a standard questionnaire to help doctors, nurses and midwives better gauge a woman's symptoms and risk in the early stages of her pregnancy to identify those likely to develop mental health problems and intervene early.

The guidelines also stress the importance of assessing a woman's psychosocial risk factors.

"It's about screening for symptoms but also considering the context of a woman," the chairwoman of the guideline's expert working group and St John of God chairwoman of Perinatal and Women's Mental Health Research Unit at UNSW Professor Marie-Paule Austin said

"If there are aspects of her life that make her more likely to develop these problems," said the psychiatrist, who developed the risk factor questionnaire at the Royal Hospital for Women.

By embedding mental health screening as a routine part of maternity care, the authors hoped to cut through the entrenched stigma that often prevents pregnant women from seeking help.

"We are validating their right to talk about these things ... our surveys found a huge proportion of women are really glad they are asked these questions," Professor Austin said.

The guidelines went beyond the prevailing focus on depression and anxiety, the most common disorders among women during and after pregnancy.

But a smaller group will develop more severe psychiatric conditions, including postpartum psychosis, and an estimated 5 per cent of women of child bearing age have borderline personality disorder.

"These women can experience intense and severe fluctuations in mood, self-loathing, even self-harm and feel a great sense of alienation," Professor Austin said.

"It's hugely challenging to take on the parenting role."

The guidelines were also designed to debunk ill-informed clinical advice, notably the pervading belief that women should come off medications for psychiatric conditions when they become pregnant.

"Often clinicians will tell women to stop taking their medications, predominantly antidepressants ... and it's not uncommon for them to relapse," Professor Austin said.

But antidepressants are not associated with birth defects and there was a lack of robust research linking them to child's emotional and behavioural outcomes.

The desire to stop taking medications must be weighed against the negative effects of mental ill-health in pregnancy, Professor Austin said.

The guidelines also consider role of a woman's partner as support person, potential antagonist, as well as the effects of the pregnancy on their mental health.

Initially screening a woman without her partner present gives her the privacy to talk freely, before the partner is invited to join the consultation, with her consent.

From November, all women have access to free depression screening and psychosocial assessment through Medicare.

The move, in step with the guidelines was the "final piece of the jigsaw," Professor Austin said.

* Not her real name.