Lecturers' union Natfhe has stepped up its campaign against pay bars for nursing lecturers.
A number of universities are in the process of dropping the rules, which stop nursing lecturers from progressing beyond a certain pay scale.
Jenny Golden, Natfhe regional official, said: "No other academic subject has pay bars and as nursing is predominantly a female profession then their imposition could open the way to equal-pay cases."
The bars were imposed as part of complex contract negotiations when nurse educators moved from the National Health Service into universities.
Greenwich University is set to remove the bar. A spokesperson said: "As part of complex contractual negotiations, the university undertook to honour all the pay and benefits expectations that NHS staff had enjoyed in their former employment - including the right to salary progression up to the maximum that they would have been paid had they stayed in the NHS."
The university has been in negotiation with Natfhe to remove the bar. "Former NHS staff have gone through a significant period of transition in order to adjust to the duties and responsibilities of a teacher in higher education - which are broader than those that had been required of nurse educators - and the changing framework of nurse training, which now demands degree-level study."
In the intervening years the university has reviewed the position of individual staff who have taken on management responsibilities and allowed them to progress beyond the bar.
Sheila Withams, dean of Homerton School of Health Studies, said: "We dropped the pay bar a year ago when we renegotiated teaching staff contracts with Natfhe.
"These contracts are now in line with other higher education contracts. We wanted more from senior lecturers and the new contracts reflect that."
A spokesman for the Council of Deans of Nursing said: "Recruitment of nursing lecturers is becoming more difficult because of the increased differences between academic and NHS pay scales."
He said that the use of teaching-only contracts in old universities was also a serious issue, holding back nursing research.
Ms Golden said: "There are people who have done MAs and doctorates who are being held back by the pay bar."