Some Thoughts on Birth Control

Alright, this is going to sound really wierd.
Most of the west sees the advent of the birth control pill as an unqualified good. It is believed to help people control their reproductive choices and so give them more control over their lives. It is seen as certainly lifting peple out of poverty, since children are certainly expensive to raise. The west is also concerned about a population explosion and an increasing scarcity of resources. For these reasons, the birth control pill and other products available are generally promoted in our culture.
But in other parts of the world, reproduction goes on. Live births in other parts of the world, especially the third world, far outstrip western cultures. To paraphrase 'the Doors,' we may have the guns, but they have the numbers.
Even in Europe, the West risks the danger of being outnumbered in coming generations by immigrant populations that do not share its values. England, France, Holland, and Germany are already beginning to experience some negative impacts of this phenomenon. Immigrant populations are becoming increasingly powerful in those countries. Some have speculated that in the next few generations Europe, along with its western values, may be overcome politically by the sheer numbers of these immigrant populations. It makes me wonder, has the west sewn the seeds of its own destruction by its position on birth control.
In America, where birth control has been wildly popular, we are beginning to experience the pangs of relative underpopulation. Our social security system relies on the replacement of workers to keep the system solvent. When the system was started there were roughly 15 workers for each retiree. Today that number is something like three to one. When the baby boomers begin to retire that number will shrink considerably. The only way to keep the system solvent, especially since our politicians have plundered whatever could have been saved and invested, is to either raise taxes on the working or increase immigration at an alarming rate. But these solutions will not work.
It used to be that every family had a built in social security policy. Parents would have children and care for them when they were young, and later the children would care for the parents. Ideally, large families insured the security of the parents. Now that the responsibility has shifted to the government, people have turned, mostly for reasons of convenience, to a model of 2.3 children. This is not enough to sustain Social Security.
I personally know people who have opted to have no children at all because they wanted their freedom and a healthy disposable income to spend on toys. In reality they are like children themselves who don't want to grow up. These people usually gripe and moan about welfare programs for children that they are forced to pay for through taxation. Ironically, it is these children, the ones about whom they complain, that will probably be supporting them in their old age.
Through birth control, has the west forgotten a fundamental principle of human existence? Does society need to multiply in order to sustain itself?
In the garden, God said to our first parents, "be fruitful and multiply." In my opinion, our culture tend to think of sex as being primarily for pleasure. Certainly this is one purpose. Sex does provide pleasure and strengthens the bonds of marriage. But have we unwisely eliminated one of God's purposes for sex, the propagation of the race? Will the west pay the consequences for this turn in our culture?