There are plenty of reasons to quit smoking. The health effects of smoking are well known and well documented, not just on your fertility, but a whole number of health issues including heart disease and cancer. Now, there's yet another reason to quit smoking if you are pregnant or trying to get pregnant. Cigarettes may actually affect a woman's male offspring's sperm quality. As reported in Human Reproduction, the male offspring of pregnant mice exposed to high levels of cigarette smoke had sperm with lower counts, lower motility and more abnormally shaped sperm (low morphology), and these male mice took longer longer to impregnate female mice who in turn gave birth to fewer mouse pups. So, what does this all mean? While we don't yet know if this is true in humans (or even 100 % sure it is true in animals), exposure to tobacco smoke could not only harm your fertility (among other things) but also could harm your unborn son's chances of fathering children. This is another good reason to quit.