The sex life of Superman and Lois Lane has often caused commentary over the decades. While originally studiously avoided by the comic books, sci-fi writer Larry Niven wrote the essay Man Of Steel, Woman Of Kleenex, published in 1969, which envisaged all sorts of unfortunate results.
Electroencephalograms taken of men and women during sexual intercourse show that orgasm resembles "a kind of pleasurable epileptic attack." One loses control over one's muscles. Superman has been known to leave his fingerprints in steel and in hardened concrete, accidentally. What would he do to the woman in his arms during what amounts to an epileptic fit?
Consider the driving urge between a man and a woman, the monomaniacal urge to achieve greater and greater penetration. Remember also that we are dealing with kryptonian muscles. Superman would literally crush LL's body in his arms, while simultaneously ripping her open from crotch to sternum, gutting her like a trout. Lastly, he'd blow off the top of her head. Ejaculation of semen is entirely involuntary in the human male, and in all other forms of terrestrial life. It would be unreasonable to assume otherwise for a kryptonian. But with kryptonian muscles behind it, Kal-El's semen would emerge with the muzzle velocity of a machine gun bullet.
It was a different time, etc. In the time since, Lois Lane has given birth to Superman's child – with special care to avoid what Larry Niven described thus;
Can the infant use his X-ray vision before birth? After all, with such a power he can probably see through his own closed eyelids. That would leave LL sterile. If the kid starts using heat vision, things get even worse. But when he starts to kick, it's all over. He will kick his way out into open air, killing himself and his mother.
Niven also offered his solutions to some of these dilemmas, which included a pregnant Superman. Kevin Smith also revisited these issues (or tissues) in Mallrats.
Frank Miller, in The Dark Knight Strikes Back included this scene:
Lara: So what about sex?
Superman: Never with Terrans. They're too fragile.
Preferring to have Superman with Wonder Woman.
Something Dan DiDio and Jim Lee preferred too for the New 52, pairing Lois Lane up with a mere human, Jonathan Carroll, never seen again and possibly buried under the Fortress of Solitude by Superman in a jealous mood.
But the reviews from Wonder Woman in various continuities were good. Five stars. But in recent decades, DC Comics have just ignored (most) of these issues. And so Clark and Lois had a kid together – the normal way. Superman was, after all, red, white and blue-blooded.
But in today's Future State: Superman Vs Imperious Rex #2 published by DC Comics today, it seems that in the future, Clark Kent's star rating may have slipped a little.
Looks like Superman still has his super-speed intact at least.
FUTURE STATE SUPERMAN VS IMPERIOUS LEX #2 (OF 3) CVR A YANICK PAQUETTE
(W) Mark Russell (A) Steve Pugh (CA) Yanick Paquette
It's really happening: Lexor has joined the United Planets! While surveying, Lois Lane and Superman discover that the planet is rich in minerals, causing Lex Luthor to try and exit the federation to make a pretty penny! Realizing he can't leave without agreement from Earth, he imprisons Lois Lane, then whips up the propaganda machine against Superman. Now the power couple must work together to break free and stop Luthor's plans! But how can they fight a whole planet that's designed to hate them?