Want title for scifi magazine short story circa 1971 about planet depopulation.?

Question

This story appeared in one of those scifi mags of the day like "Asimov" or something similar. Story was about a scientist who developed something that rendered 99.9% of the planet's population sterile. As time went on the planet spiraled downward in population, cities were dismantled, people went back to their indigenous homelands.
I've looked and looked, can't find it or what it might be.
Thanks or thanks anyway.
Bliss!
Sandman

Answer 1

Doesn't sound familiar, but this link lists Hugo award winners for short stories, and it might jog your memory. Harlan Ellison was king of short stories back then.
http://en.wikipedia.org/wiki/Hugo_Award_for_Best_Short_Story