No one should be able to play God and say that they can't have children. Children are a blessing from God not a curse. In China I have heard they give forced abortions and also many many children are thrown away like trash in ran down orphanages because they have a limit of 1 child per a house. If we would seek and trust God he would meet are needs. Many people kill there babies because it isn't convenient or easy- what a sin.
I know this may not be exactly what you meant but this is the direction I chose to go with your question. The more limits we put on humans right to reproduce babies being born will equal to more blood on our hands/their hands. There is nothing wrong with planning and taking preventative steps but still it isn't a %100 guarantee of total population control. Once a law is put in order for the sake of population control it will quickly lead to playing God and killing babies when it is out of their control. This is what I think . :)