What is Child Benefit for? 
Many people, especially those not in employment believe that to receive the benefit is their right and that the state should help them to afford to look after their children.  If the state was forcing them to have children, then I would agree, but the state is not.
To have children is the individual choice of 2 persons, in making that choice, should be, can we afford to have children and if so how many. Not I want so many children and then I expect the state to contribute to their up bringing. There are even people who have children, just to increase the amount of child benefit they can get and many of these people will be unemployed.
If you can not afford to look after children then do not have them.