New mothers suffering from postnatal depression or other mental health conditions could be given extra support under a £60 million plan set out by NHS England.
Under the plan, £40 million will be shared to fund new community mental health services in 20 areas, with a further £20 million to be allocated next year.
There will also be a new standard for treating people experiencing a mental health crisis in A&E departments or a hospital ward, with a recommendation that they should be seen by a specialist within an hour of being referred.
NHS England chief executive Simon Stevens said: "For most parents having a baby is one of the happiest times of your life.
"But for tens of thousands of new mums, this experience is sadly overshadowed by severe pregnancy-related mental health problems.
"Now the NHS is taking concrete action to get these mothers and families the specialist mental health support they need.
"It is also the case that many other patients with mental health crises end up using A&E services as their first port of call, so today we are kick-starting the programme to expand the seven-day availability of specialist psychiatrist and mental health staff in our major A&Es."
The first £40 million of funding for perinatal community mental health schemes will be allocated to 20 areas, helping reach 30,000 more women a year by 2021.
The funding will see new or bigger teams in those areas providing specialist care for all new and expectant mums with severe mental ill health like severe postnatal depression.
Under the new recommended standard for people suffering a mental health crisis, anyone who arrives at an A&E unit or is already on a hospital ward should be seen by a specialist mental health professional within an hour of being referred.
Within four hours they should have been properly assessed, with the next steps for their care planned in partnership with them.
Regional A&E delivery boards can bid for a share of £30 million of funding for psychiatrists and mental health nurses to provide better care for people with urgent and emergency mental health needs attending A&E or being treated on general hospital wards.
Professor Lesley Regan, president of the Royal College of Obstetricians and Gynaecologists, welcomed NHS England's announcement.
She said: "Around one in five women develop a mental illness during pregnancy or in the first year after delivering their baby and one quarter of all maternal deaths between six weeks and a year after childbirth are related to mental health problems.
"Despite these alarming figures, in almost half of the UK pregnant women and new mothers have no access to specialist maternal mental health services and only 3% of clinical commissioning groups (CCGs) have a maternal mental health service strategy.
"This initiative will not only provide invaluable support to women in the community, but also ensure that women can be referred to specialist services in a timely manner.
"Buddying and telephone support initiatives will also ensure that women feel able to share their own experiences and prevent feelings of isolation."
She added: "Giving parity of esteem to mental and physical health is crucial and we have some way to go in addressing the stigma associated with mental health.
"Many women often fear being seen as a 'bad mother' and having their child taken away from them.
"Women are frequently made to feel guilty that they are to blame and that they have failed to be the 'perfect mother'.
"No one is to blame for developing a mental health illness and as a society we need to be reinforcing this message constantly."