I'm almost 30, been carrying a cell phone since I was 16. The mother of my child, same thing. At the time of conception (we were both mid-late 20's), we were drinking like fish, smoking a half pack a day, eating horribly, for whatever reason we were both in great shape (I exercise a lot, she was very into dancing), using protection (not as well as we thought apparently) and bam, shes pregnant.
There was a list on thebump.com or some such website, listing all the do's and don'ts for getting pregnant, we pretty much broke every rule both ways, weren't trying, and now we have a child.
I think the bigger problem with fertility will be overweight/obese people more than anything else. I have friends who have been trying to months/years, no luck. There seems to be a strong correlation between weight and fertility, at least in my anecdotal experience.
Obesity is linked with low testosterone in men, and normal levels of testosterone are necessary for good sperm production and fertility (testosterone treatments have the opposite effect) so I think this is correct.
On the other hand, if worst comes to worst, maybe they will carry cell phones in their ankles?