"The current evidence indicates a 9% prevalence of infertility (of 12 months) with 56% of couples seeking medical care. These estimates are lower than those typically cited and are remarkably similar between more and less developed countries."
I mention this because this turned up on google news:
Containing this sentence:
"Infertility affects about 13 to 14 percent of couples worldwide."
Which I thought sounded ... off, on the high side. It's not obvious how comparable the two statistics are, because some studies look infertility as an attribute of a woman (who is not getting pregnant) and others look at it as an attribute of a couple. I could imagine the rate at which couples are infertile exceeds the rate at which women are infertile -- but I don't really think the studies are doing a great job of ascertaining either one specifically.