Over 20% of births worldwide result from pregnancies women did not wish to occur.
It is estimated that 215 million women in developing countries are sexually active, but don't want to become pregnant; in other words, they have an unmet need for family planning.
More research and a public better educated about sexuality and reproduction could engender a global social movement that would make possible a world of intended pregnancies and births.
Before, we didn't know how to control pregnancy, we didn't have the education, and people in the area were having nine or ten children.
The world could possibly reduce consumption down to a very basic level, but if population keeps growing, eventually that will not be enough.
Even today many are living on a sub-sustainable level, due in part to an uneven distribution of resources, but also because, in many regions, population has outgrown essential resources for that region.
When people feel threatened by a hand-to-mouth existence, they are more likely to look towards less-than democratic ways to reduce population, especially if they have the foresight to realize that population growth is like a run-away train, very difficult to slow and stop.