What's wrong with the suggestion? Well, here's one thing: The instant anyone in those countries discovers what you're doing, I expect one of two things will hap

What's wrong with the suggestion? Well, here's one thing: The instant anyone in those countries discovers what you're doing, I expect one of two things will happen. Either (1) they will completely stop accepting your aid, in which case whatever good you were hoping it would do is right out of the window, or (2) you will suddenly find a whole lot more terrorists looking to do a lot of damage in rich countries. More simply, you might just like to imagine how you'd feel if the roles were reversed. So, e.g., let's suppose that the Chinese government said: "All these Westerners are relying on our services to make lots of super-cheap goods. Why don't we put something in the plastic that makes them less fertile? It's for their own good." And let's suppose that you have been trying to have children for a few years and failing (or some close friend or relation has been) when you discover this. How do you feel? A few other obvious things that I hope you missed: (1) Different people are fertile to different extents, and if you lower the average fertility you're most likely making lots of people completely infertile. (2) Your measures are going to affect the extra-specially poor disproportionately. To make a whole country's average fertility go down to replacement level, it may have to reduce the fertility of those people much more drastically. Down to zero, perhaps. (3) Having children is really, really important to a lot of people. You may think that's irrational; you may even be right; but that's how it is, and that's why you'd most likely get the effects I described above. (4) Having to make a choice between two horrible alternatives -- e.g., starving versus sterilization (see #2 for why it might really be pretty much exactly that choice) is, for many people, substantially worse than the better of those two alternatives. (See, e.g., "Sophie's Choice".)