The midwives, members of the Midwifery Employee Representation and Advisory Service union, will walk off the job twice a day, for two hours a time, for a fortnight.
Today's first strike runs from noon to 2pm, and Dunedin MERAS members will stage a rally in the Octagon.
The Southern District Health Board said patient safety was its priority, and it was working to minimise the impact of the strike on women and their babies.
''Other Lead Maternity Carers (LMCs), including community LMCs midwives, are not part of the strike action and will continue to provide care and carry out duties as usual,'' a statement said.
MERAS Dunedin organiser Michelle Archer said there was a national shortage of midwives and members were worried about attracting new midwives to the profession.
''At the moment a midwifery degree is a year longer than nursing, it's essentially $10-$25,000 dearer, yet you're not being remunerated effectively in the pay structure.''
A vote by MERAS midwives led to them rejecting a proposed 9% pay rise over 18 months, two pay step increases and a lump-sum payment by a sizeable margin.
Ms Archer said the midwives' key demands were for their profession to be recognised as important, and distinct from nursing - issues she felt the pay offer did not address.
''We're not comparing ourselves to nurses - we're comparing ourselves to the role and responsibility we have, to the pay-scale we are on,'' Ms Archer said.
''The professions are very different and have very different scopes of practice . . . every time we see someone we are responsible for two lives, not one - we want our pay structure to recognise that.''
Midwives would be available to provide life-preserving services.
Meanwhile, the New Zealand College of Midwives has backed today's strike.
''This is only the second time in history midwives have taken the decision to strike,'' college chief executive Karen Guilliland said.
''This has been a very difficult decision for midwives to make and the college supports the employed (DHB) midwives 100%,'' she said.
''Midwives working in hospitals are facing critical workforce shortages and deserve recognition as the distinct and specialised profession that they are.''
