She said the fact some DHBs had requested more midwives than would normally be rostered on duty highlighted the severe under-staffing of maternity units around the country.
"The union is being asked to find members willing to fill gaps in rosters," Conroy said.
"It is not the purpose of LPS to fix staffing shortages."
MERAS industrial co-leader Jill Ovens said DHBs and the Ministry of Health are holding their position that members should accept the nurses' pay scales.
These were agreed as a result of a negotiation in which the bulk of midwives employed by DHBs and represented by MERAS had no part.
"Midwives and nurses are health professionals and key members of a team that works hard to deliver the best outcomes for women and their babies," Ovens said.
"A decision by members of MERAS not to accept a DHB pay offer has nothing to do with being worth more, less or the same as nurses."
Ovens said they have a different code of practice, different expertise and a different history to nurses.
"Other health professionals like physiotherapists and occupational therapists have pay differentials that reflect their qualifications, level of responsibility and scope of practice.
"Why shouldn't midwives have their pay rates set in the same way?"
