This debate has been going on for years and years. How could Superman and Lois Lane possibly conceive a child?
We all know that if Superman and Lois had sex, Kal's super sperm would blow a hole clean through sweet Lois' thinking cap and if by some chance it doesn't and a child were conceived, that baby would almost definitely kick a hole clean through old miss Lane's tummy. However, there are a few ways the two could conceive a child without putting Lois' safety at risk.
1: Superman could set a room in the Fortress to emit Red sun energy. This would completely strip Kal of his powers for as long as he stayed in the room, which for safety's sake would need to be at least 24 hours before doing the horizontal mambo with Lois. After this Lois would need to remain in the room for the entire period of her pregnancy.
2. Build a Fortress of Solitude on the Dark side of the moon with it's own atmosphere. The Dark side of the moon gets no sun light, and with Supes being a living solar battery, his powers would be gone after about 24 hours without Solar recharging. Of course this would mean that he'd have to leave poor Lois on the Moon for the duration of her pregnancy which is unacceptable and would also mean that in order for him to recharge his powers, he would need to use a spaceship to get back to Earth.
3. Kryptonians have obviously been to Earth before and know that humans are fragile in comparison to themselves. Obviously, Kal-El wouldn't be the first Kryptonian to fancy an Earthling so much they'd wanna get in their pants. Krypton is full of extremely intelligent scientists who could obviously develop a way for Kryptonians and Humans to not only do the dirty but also procreate. A device as simple as a wrist band could have been developed for both the human and Kryptonian to wear during intercourse. The Kryptonian's bracelet could suppress their powers while the human's bracelet could suppress the developing powers of any fetus growing inside them. For a Kryptonian scientist, this would be as simple to construct as a deep water suit for human scientists. With Jor-El sending his son to Earth, he would have surely known that eventually his little Kal would start getting hair in funny places and thinking of girls, so obviously he would have included a device like this in Kal's space ship when he shot him from Krypton.
4. Superman and Lois could simply ask Zatanna to cast a spell that would suppress Supe's powers when they got in the mood, and the same spell would affect any offspring Lois and Clark may conceive to the point where their powers are suppressed while in utero.
Now most of these answers take the assumption that Kryptonians begin developing their powers from the moment of conception. However, in many sources Kal-El's powers didn't develop until he reached puberty. If the latter is true of all Kryptonians, then obviously baby El would be as normal as a human while in Lois' tummy, which means there would be absolutely no need for Lois to remain on the Dark Side of the moon, in solitary confinement in the Fortress of Solitude, have a spell cast over her or even need to wear such a Kryptonian device to protect her.
If all else fails, there's always the approach that All Star Superman took. Turn Lois into Ultra Woman for 24 hours, so the two could have Superman sex and then let nature take it's course.
