They were sensible in implimenting it, however, they were also far too strict with it, increasing infancide of young girls and making women well into their pregnancies, have abortions. Young chinese boys became "little emporers" because they were so badly spoilt and fussed over by their parents. People in rural areas were allowed two children to help in the fields, there were a few other exceptions aswell, such as parents of disabled children were allowed another child and twins were allowed to be kept.
Another strict rule implimented as part of the one child policy was that
women had to be over 20 to get married, men had to be 22.
I definitely think that their population needed to decrease...1.2 billion people living in china...That's 20% of the world population and the resources of the country were not enough to support all of it's population so they estimated that if the population reached 1.5 billion many chinese would be living in poverty.
I don't think, however, that such extreme measures (infancide, late abortions etc) needed to be taken in order to achieve their 1 billion target.
Right, sorry about that

I know a fair bit about the whole one child thing for one reason or another and i'm really into geography