[gcheong]

Not necessarily. Birthrates in developed countries where resources are plentiful and infant mortality rates are low tend downward, not upward. Our species has adopted the strategy that it is better to put more resources into fewer offspring than the shot-gunning approach. We only need to maintain replacement levels or slightly above to be self-sustaining.

[robryan]

Apart from isolated examples in certain countries I don't think the world as a whole has much to worry about in maintaining replacement levels.

[Luyt]

6,873,900,000 and counting... (continuous growth since the Black Death around the year 1400)

http://en.wikipedia.org/wiki/World_population