From "Man of Steel, Women of Kleenex", by Larry Niven...
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VI
A ripened but unfertilized egg leaves LL's ovary, begins its voyage down her Fallopian tube.
Some time later, tens of millions of sperm, released from a test tube, begin their own voyage up LL's Fallopian tube.
The magic moment approaches...
Can human breed with kryptonian? Do we even use the same genetic code? On the face of it, LL could more easily breed with an ear of corn than with Kal-El. But coincidence does happen. If the genes match...
One sperm arrives before the others. It penetrates the egg, forms a lump on it's surface, the cell wall now thickens to prevent other sperm From entering. Within the now-fertilized egg, changes take place...
And ten million kryptonian sperm arrive slightly late.
Were they human sperm, they would be out of luck. But these tiny blind things are more powerful than a locomotive. A thickened cell wall won't stop them. They will *all* enter the egg, obliterating it entirely in an orgy of microscopic gang rape. So much for artificial insemination.
But LL's problems are just beginning.
VII
Within her body there are still tens of millions of frustrated kryptonian sperm. The single egg is now too diffuse to be a target. The sperm scatter.
They scatter without regard to what is in their path. They leave curved channels, microscopically small. Presently all will have found their way to the open air.
That leaves LL with several million microscopic perforations all leading deep into her abdomen. Most of the channels will intersect one or more loops of intestine.
Peritonitis is inevitable. LL becomes desperately ill.
Meanwhile, tens of millions of sperm swarm in the air over Metropolis.
VIII
This is more serious than it looks.
Consider: these sperm are virtually indestructible. Within days or weeks they will die for lack of nourishment. Meanwhile they cannot be affected by heat, cold, vacuum, toxins, or anything short of green kryptonite.
(*And other forms of kryptonite. For instance, there are chunks of red kryptonite that make giants of kryptonians. Imagine ten million earthworm size spermatozoa swarming over a Metropolis beach, diving to fertilize the beach balls... but I digress.*) There they are, minuscule but dangerous; for each has supernormal powers.
Metropolis is shaken by tiny sonic booms. Wormholes, charred by meteoric heat, sprout magically in all kinds of things: plate glass, masonry, antique ceramics, electric mixers, wood, household pets, and citizens. Some of the sperm will crack lightspeed. The Metropolis night comes alive with a network of narrow, eerie blue lines of Cherenkov radiation.
And women whom Superman has never met find themselves in a delicate condition.
Consider: LL won't get pregnant because there were too many of the blind mindless beasts. But whenever one sperm approaches an unfertilized human egg in its panic flight, it will attack.
How close is close enough? A few centimeters? Are sperm attracted by chemical cues? It seems likely. Metropolis had a population of millions; and kryptonian sperm could travel a long and crooked path, billions of miles, before it gives up and dies.
Several thousand blessed events seem not unlikely.
(*If the pubescent Superboy plays with himself, we have the same problem over Smallville.*)<more>
http://www.larryniven.org/stories/Man_of_Steel_Woman_of_Kleenex.shtml Meethinks Superman needs to fly to the dark side of the Moon before breaking out the porn collection.