I don't know. I've just read that it's one child per family, all other children have to be euthenased (sp?), however, as most families cannot afford the euthanasia, they are often just left on the streets. This may be exadurated, as I never heard this from a very reputable source, but due to Chinese tradition, it's always an "honour" to have a male child - so fathers often dispose of their female babies, and try harder for male babies. This has caused the 70/30 male to female ratio.