Sheyna Huband credits midwife Jacqui Anderson, left, with giving her support and confidence ahead of the birth of her third son, Oliver.

Hundreds of midwives will file court action on Monday to sue the Government for paying them less because they're women.

The College of Midwives warns that if things don't change fast, the pay crisis will leave many pregnant women without a midwife to deliver their baby.

The college will lodge the nation's biggest equal pay challenge in the High Court at Wellington, alleging the Ministry of Health's pay levels breach gender rules under the New Zealand Bill of Rights Act.

The case will be led by prominent lawyer Mai Chen.

College chief executive Karen Guilliland said discrimination against midwives had actually worsened. "This claim has been almost 20 years in the making. The legal action will have global ramifications."

Self-employed midwives typically look after about 50 expectant mums a year and are paid about $100,000 annually by the ministry, but earn an average of $53,000 before tax because of various expenses they have to cover as a business, and their wages do not increase to match their experience.

Midwives earned less in their pockets than receptionists, Guilliland said, yet held the nation's future in their hands. "We are really concerned about our ability to maintain the service."

Midwives were on call 24 hours a day, seven days a week, and were responsible if anything went awry with the pregnancy or birth, she said.

New Zealand has about 3000 registered midwives and a third were Lead Maternity Carers (LMCs), who delivered 90 per cent of the country's babies.

Guilliland said it would claim in court that the female-dominated profession was financially unsustainable.

Experienced midwives were leaving the profession in droves, and many newly graduated midwives were choosing to work for DHBs rather than become LMCs. "One newly graduated midwife said to me the other day 'I love my job, but didn't realise I'd signed up to be a slave'."

Pay experts found midwives earned about 60 per cent less than male-dominated professions that required a similar level of qualifications, skills, expertise and responsibility.

The ministry offered a $2.1 million increase in the Budget for for LMCs, which would increase at the same rate for four years.

Guilliland said: "$41 a baby after 19 years with no substantial increase was too little, too late."

In some areas, pregnant women already struggled to find a midwife because of dwindling numbers, she said.

In the past, GPs offered maternity care for women in the community, but that changed 25 years ago when midwives gained the legal right to claim for their services. Now, only 18 GPs were classed as LMCs, compared with about 1000 midwives, 99.9 per cent of whom are women.

Guilliland said midwifery care had become increasingly complex, yet the pay rates failed to compensate for the additional requirements.

The National Council of Women of New Zealand supported the college's "bravery" in taking legal action over what it saw as structural sexism.

Council president Rae Duff said despite the progress made over the years towards gender equality, discrimination still persisted, including in the work place.

The issues the College of Midwives' legal case raised were "long-term, systemic and transcend party politics."

'THERE ARE MIDWIVES THAT ARE WALKING AWAY'

Jacqui Anderson, who has been a midwife in Canterbury for 30 years, said the pressure midwives were under kept increasing, but much of the work they did was invisible because it was seen as just "women's work with women".

Remuneration was not keeping up with the increased workload, and some midwives were finding it hard to sustain their practices, she said. "I know for a lot of midwives, there's expectations that they'll do more for less. It's becoming a point where midwives feel they're paying to do the jobs.

"There are midwives that are walking away – that's putting pressure on those left, they're having to take on more clients. People lose heart."

The low pay rates made it hard to attract new people to the profession, which was facing an aging workforce like the rest of the health sector, Anderson said.

"We do have a lot of women interested in midwifery ... but they want to know their worth will be recognised at the end.

"We've got a world-class, world-leading midwifery service because of the ability to provide continuity of care. All these things are definitely going to be put in jeopardy."

Anderson was the midwife for two of Christchurch woman Sheyna Huband's three children. Her youngest, Oliver, was born two-and-a-half weeks ago at their North Beach home.

"I suffered from post-natal depression with my first child so having a good midwife, for me, was really important. I wanted a positive birth experience."

Anderson was there to answer all the questions she had, address any concerns, and give her confidence, Huband said.

"I always felt like there was someone that I could talk to. We rely really heavily on our midwives as our primary carer – they're charged with helping bring life into the world. I don't think we can overvalue that."