HMRC have advised that from April 2017 both the child element of Universal Credit, as well as the individual element of Child Tax Credits, will be limited to a maximum of 2 children!
Please note that this will affect new claims only - if you are already receiving benefits for more than 2 children, you will continue to get the same level of support.
There are some exceptions to the new rules, i.e. multiple births, and further details can be found on the HMRC website here.
These changes have been introduced as part of the Welfare Reform and Work Act 2016.