So long as the family planning policies are educational and voluntary, I think that it would be a good idea for countries that are growing rapidly to create family planning policies.
As I said in my answer to your other question, compulsory family planning goes against basic human rights. However, if the government can persuade people to limit the size of their families, there is much less reason to worry about a loss of human rights. The government should simply inform people about the benefits of having smaller families and, perhaps, give them easy access to contraceptives so that they can limit their family sizes if they so choose. So long as the government does this, it will not be forcing people to do anything and will therefore not be infringing on their human rights.
Studies have shown that the less control a woman has over the number of children (i.e. family planning) the more likelihood the country she lives in is rated as third world living. Those societies that have advanced family planning options, such as access to birth control in lower income women have been shown to be substantially better econmically.