Actually the factors inhibiting birth rate are well known, but the actions to take are not something states wants to take. In Europe you cannot even talk about it, usually, unless you talk to younger family members and ask them why they don't want kids at or or just 1 or 2 max. There are economic, education and legal aspects that are clear for anyone that looked not farther than 50 years ago when having 3-4 kids was not exceptional.