Obesity effects EVERY system of your body, to some degree... However, its effect is different from person to person.
I doubt that being slightly over weight will effect your chances of getting pregnant. However i'd guess that if you had a real obecity problem then yes it would due to your body being unhealthy. Your body knows when its not prepared for kids. And chances are if you really are obese (to the point where it would have an effect on getting prgnant) then its an unsafe weight to be pregnant to. Your body becomes very fragile in pregnancy (as does the childs) and obesity allready puts such a strain on your heart and body that i wouldnt think it was a good thing. (but this is all just a guess) However if you were just "over weight" then no i wouldnt imagine it would have much effect on your chances of getting pregnant.
There is a woman my husband works with (actually, a boss of his) whom is very obese, she is 7 months pregnant, and no one noticed. She finally had to make an announcement. =P I think obesity does more to harm the body and baby during pregnancy than it does in restrict fertilization. But I'm no expert...
