Our country currently does not have a sustainable population, i think it hovers around the 1.7 per couple mark, that is why we have such a high immigration rate. Saying that we would consume resources and space at a greater rate is rediculous, our government even considers australia to be a little underpopulated, we need a larger workforce to push the ecconomy and we dont have the population to do it.
Some sort of radical ban on contraception, ban on abortion thing would be enough to give our country the boost it needs. Promoting frivlous abortions is something our country does not need, an extra 70 000 births a year would help us considerably.