As someone who thinks systematically about the future for a living, I frequently read science fiction with an eye for what it reveals about how today's real fears are being projected upon tomorrow's imagined landscapes. The books behind the 1973 movie "Soylent Green" (too many people!) and the 2006 movie "Children of Men" (no more babies!) make for a good example. Compare their central premises and you've basically captured the 180-degree turn the popular imagination has experienced on population growth over my lifetime.
So what does today's science fiction tell me? We have a lot of fears about biological technology racing ahead of our political and social ability to deal with it. A very popular vein for a while now has been the future dystopia in which private corporations and/or scary government agencies control access to fabulous drugs and gene-manipulating technologies that allow the lucky few to live long and prosper, while the masses are condemned to "getting by" by getting high. In other words, a defensible screen capture of today's extremities, extrapolated grimly into decades ahead.
When you track the breakthroughs and projections in this realm, it all sounds fairly plausible, especially if you're a cynic about human nature and politics (e.g., "rising" China as a harbinger of future authoritarian trends). For example, scientists are getting ever closer to understanding how to dramatically slow down the aging process, targeting future drugs that will mimic the conditions of radically reduced caloric intake. Then there's cutting-edge research wherein stem cells are being reprogrammed to generate replacement tissue, making wholesale restocking of the human body theoretically possible -- if you've got the money or right insurance.