Nelson-Marlborough Health Board had the lowest uptake of only 22 per cent, followed by Waikato and Lakes DHBs at 23 per cent.
Maternity Services Consumer Council researcher Lynda Williams said some midwives were dubious because of a lack of evidence about the efficacy of vaccination.
"It is an informed consent issue," Williams said. "The board may take measures to encourage staff, or say those that aren't vaccinated can't work with the elderly or babies but, in the end, it is a person's right to decline the vaccine."
Nelson-Marlborough Health Board director of nursing and midwifery Robyn Henderson was surprised and disappointed to see the low figure.
She said some midwives may be getting vaccinated outside the hospital and others may be allergic to the vaccine.
"Midwives specifically take the notion of immunisation really seriously so I can't understand that that figure is right," Henderson said.
The board strongly encouraged midwives to be vaccinated to protect mothers, babies and themselves. "If those figures are right then we need to do more to ensure staff have more access to flu immunisations by taking it to the people."
Waikato District Health Board spokeswoman Bethany Pawson said the board created "vaccination champions" this year after seeing the figures. Each department had someone who could administer the vaccine, making it more accessible for busy medical professionals.
The founder of Action To Improve Maternity, Jenn Hooper, said she believed the flu vaccination rate was also low among independent midwives.
"Midwives tend to follow science less than other medical professionals because birth is a natural process."
40 years without jabs
Independent midwife Denise Hynd has worked with pregnant women and babies for more than 40 years.
During that time she has never been vaccinated against influenza.
Hynd, 59, said she was vaccinated against some diseases such as hepatitis B, but not influenza. She believed there was a lack of information for informed consent under the Code of Health and Disability Services Consumers' Rights. "All the information you get is pro-vaccine. If you are going to make an informed decision you need to know the benefits and the risks," said Hynd, who is also a registered nurse.
She said immunity should be bolstered through healthy diet, exercise and infection control such as covering mouths when sneezing.
Hynd, who has worked for health boards in New Zealand, Australia and Papua New Guinea, said she had not put patients at risk.
"If I was unwell I would not attend patients. I would look after myself to get better and boost my immune system." Hynd said she encouraged patients to make their own decisions.