There will be a chance of this happening when you have intercourse with a female. Known cure is the legendary coat hanger.
The more mutations you have, the less likely it is that your baby will survive, Dead babies are still useful, if you're hungry, but live ones can be used for a decent XP job in FC, or for fancy soup. Live babies are a bit like tamagotchi... but far, far more annoying and filled with shit, quite literally.
Abortions can be got at the abortion clinic in gangland, or from a friendly passerby with a coat hanger. Most people will do it for free (it's also a job), but beware: it hurts like buggery.
If you don't want to get pregnant in the first place, use a condom, contraceptive pills or get the fancy implant that shreads your ovaries.
Happy humping campers!