Unison is considering the claim which has already been submitted by the blue collar unions.
The union is likely to suggest some additions which may be incorporated to make a comprehensive joint claim.
Changes have to be made to the national agreements to bring them into line with the new statutory entitlements introduced in the Trade Union Reform and Employment Rights Act 1993.
The blue collar unions submitted a claim in June calling for 40 weeks maternity leave for all female manual workers regardless of length of service or hours worked.
The three parties are likely to meet for the first talks on the issue next month.
Both the Local Government Management Board and Unison view the tripartite talks as a useful step towards the longer term goal of bringing together the two negotiating groups in single table bargaining.
In Scotland the Convention of Scottish Local Authorities cites the new maternity leave legislation as the kind of issue which will be discussed in a new employer/union joint forum it is setting up.
The COSLA/Trade Unions Joint Forum will bring together 12 council members appointed by the personnel services committee and 11 representatives of craft, and blue and white collar unions.
Unions representing teachers, police and fire service staff will attend forum meetings when issues under discussion affect their sectors.
The forum will be largely consultative - there are no plans to change the existing constitutional arrangements of separate bargaining groups.
'There are many issues which we have to deal with in all the separate negotiating groups which it makes sense to deal with in one forum', said COSLA Assistant Secretary Alan Cuthbertson.