maternity benefit "top up"

I was just wondering what is the normal situation regarding companies in Ireland. Do they generally pay the difference between the maternity benefit and the employees monthly wage ?

If so, are companies reviewing this in light of the increase from 18 weeks maternity to 26 from March next year ?

We do and will continue to do so. I can't say what anyone else does.

If you do a search, you will find a number of previous threads on this topic.
In my experience, there is no "norm" in the private sector in Ireland.
Lots of companies do, lots dont,

Purely depends on your contract. In some companies some employees get it and other don't. Its a perk.