It's roughly the same as the change that happened when we stopped using leaded gas, which seems to have had a huge affect on society. http://en.wikipedia.org/wiki/Tetraethyllead#Toxicity

Also it's just one relatively simple thing. Imagine we find several things that can all increase IQ by a couple points...

I've never gotten my IQ tested, but when I read about studies like these - they usually demoralize me from fear of competitive behavior. I think this leads to low self esteem, and the imagining that I have a low IQ (high marks through schooling and post graduate education, MSc, possible imposter syndrome) as my default attitude. It can be a self defeating attitude, but what it usually does is make me argue with people about IQ tests, and explain why they are not necessarily indicative of intelligence, individually or globally.

I can imagine that merely the act of measuring IQ has significant effect on the population. I can not imagine a population that exists without it, but I imagine it would also have a huge effect on society, as you similarly hypothesize about the 1-3 point increase across the population globally.

This, but also, IQ isn't an exact score, right? Wouldn't this fit snugly within the margin of error?

Not only that, but are people even still using IQ as a metric of intelligence? As I understand it IQ is only a measure of one type of intelligence. I mean I'm all for giving a child every advantage you can fathom as a parent, so I think this is still kind of cool research, but I don't see how it equates to anything truly meaningful.

It kind of just adds one more point in the "breastfeeding is good" column.

1-3 IQ points can mean the difference between living on Hamburger Helper in a tenement, and living on fresh lobster on a 300 foot yacht.

I'm kidding, btw.