>>130164630There are ways to do it. The problem is that when a heroine gets pregnant, you can't justify them getting into fights without them seeming incredibly irresponsible (see Spider-Woman). So what ends up happening is that you need to have them off of a run while they have their kid, which is real bad for comics.
One of the better characters that I think get away with it is Sophitia from Soul Calibur, and she gets away with it because she has her kids, lets them grow up a bit so when she needs to leave to stop the Soul Edge or whatever, it doesnt seem like she is being neglectful to her kids in leaving them in her hometown. This is something that is a lot harder to solve in comics, where weekly stories are expected.
