Perhaps this is how it will end. Not with a bang but with a whimper. Will science come to the rescue?

Sperm counts and teen pregnancy rates

Today, May 3 — in case you didn’t know it — is “National Day To Prevent Teen Pregnancy.” In the past decade, possibly no social program has been as dramatically effective as the effort to reduce teen pregnancy, and no results so uniformly celebrated. Between 1990 and 2000 the U.S. teen pregnancy rate plummeted by 28 percent, dropping from 117 to 84 pregnancies per 1,000 women aged 15-19. Births to teenagers are also down, as are teen abortion rates. It’s an achievement so profound and so heartening that left and right are eager to take credit for it, and both can probably do so. Child-health advocates generally acknowledge that liberal sex education and conservative abstinence initiatives are both to thank for the fact that fewer teenagers are ending up in school bathroom stalls sobbing over the results of a home pregnancy test.

What, though, if the drop in teen pregnancy isn’t a good thing, or not entirely? What if there’s a third explanation, one that has nothing to do with just-say-no campaigns or safe-sex educational posters? What if teenagers are less fertile than they used to be?

Not the girls — the boys?

This study postulated that “environmental influences,” particularly widely used chemical compounds with an impact like that of the female hormone estrogen, might be contributing to a drop in fertility among males. If true, this was obviously an alarming development, particularly given that human sperm counts are already strikingly low compared to almost any other species. “Humans have the worst sperm except for gorillas and ganders of any animal on the planet,” points out Sherman Silber, a high-profile urologist who attributes this in part to short-term female monogamy.