Granted, in a steady state of technology and a well populated territory, LOW SKILL population leads to lower standards of living and depleted resources.


This is why sensible countries have an education requirement for immigration, i.e. post secondary and with focus on understaffed sectors.


We do not want to be another England.  


The 'babies born' argument neglects to take in to account the spectrum of socio-economic backgrounds of the parents.  Which does play a part in the economics.  


30 million LOW SKILLED immigrants is a very small economic impact.  Don't believe me?  Visit an immigrant ghetto.  Liquor stores, pawn shops, off-brand grocery stores, and ethnic food markets.  No Best Buy, Starbucks, etc.


While we are at it - why don't we raise the cost of education and lower the wages.  Makes total sense.  


A slew of poor parents and their poor children really doesn't promise progress.  Just a problem transferred between countries.


And, while I'm at it, I do believe in population control.  More people does not always a better society make.