I decided to link this post from the one about population density because I think it is an interesting question but did not want to disrupt the trajectory of that discussion.
Population control is not a new tactic and is currently implemented by governments all around the world though it saw its heyday from the 1960s to the 80s. In theory population control makes sense. If somehow a country's population is limited artificially then the country is possibly preventing further poverty, illness, and alleviating a general strain on the government. Overpopulation presents a very real risk to an only moderately stable government who can only somewhat maintain and protect the interests of their people. Too many people and a country can quickly falter and crash leaving all those extra people even worse off than they were before.
And in my opinion the best form of population control is education. Tell people what's what and provide them with contraceptive choices and alternatives to surgery or abstinence. The best choice being the condom. A country can definitely stand to gain if it curbs a growing population that it cannot serve. If done properly and safely and genuinely in the interests of the people, I see nothing wrong with the practice of population control especially in AIDS ridden Africa where babies are born into death sentences.
But the history of population control is tarnished. It's a practice that is easily hijacked and used to ill ends. Not only that but in many places the world over its actual implementation has been rather draconian in measure. Uneducated people have been tricked into operations they hardly understood and in other cases bribed for very little money which they never ended up seeing. Also, I've read reports that poor provincial people in rural countries have been used as guinea pigs for contraceptives not yet approved in the countries where they were manufactured. And no doubt this is still going on somewhere.
Where does population control end and eugenics begin?