Realistically stopping poor people from making more poor people just won't happen. They're usually uneducated and most of the time they either have the baby by accident or do it to get money. Not in all cases, some just want to have a family and can't find a job, but it's impossible to come up with guidelines on who can have children or not.
There really are too many people though, the population should have stayed at the 1 billion mark IMO.
And how will the population finally peak and decline? Well, the only way any population does. Overcrowding and starvation. Now is that really any better than putting limits on how many kids you can have?