I have seen liberals frequently say things like, "I will never bring up a child in this world". There was even a group called "Zero Population Growth" (which changed thier name to Population Connection a few years back).
Conservatives have no such compulsions. In fact, religious conservatives are known for having large numbers of children, for various reasons. (religious biases towards large familes, being against birth control and/or abortion, conservative women being less likely to live outside the home, etc.)
Children tend to vote the way thier parents do, so if this pattern is followed, Democrats are going to have serious troubles down the road. In today's Opinion Journal (Wall Street Journal editoral page), there are some hard numbers to back up this theory:
http://www.opinionjournal.com/...
According to the 2004 General Social Survey, if you picked 100 unrelated politically liberal adults at random, you would find that they had, between them, 147 children. If you picked 100 conservatives, you would find 208 kids. That's a "fertility gap" of 41%. Given that about 80% of people with an identifiable party preference grow up to vote the same way as their parents, this gap translates into lots more little Republicans than little Democrats to vote in future elections.
A state that was split 50-50 between left and right in 2004 will tilt right by 2012, 54% to 46%. By 2020, it will be certifiably right-wing, 59% to 41%. A state that is currently 55-45 in favor of liberals (like California) will be 54-46 in favor of conservatives by 2020--and all for no other reason than babies.
Unless you like how America is turning into Fundieland, maybe it's time for liberals to, um, "be fruitful and multiply". Or to at least adopt.