Problematic eggs

I have one hen that I've been trying to hatch eggs from, but for some reason have had problems with them. Last year I must have tried incubating about a dozen of her eggs, which were larger than the other hens in the same pen. It seems that the chicks would develop just fine, but just before they were due to hatch, die in the shell. I'm wondering, are her eggs just too large (they're all consistently the same size), or could there be something else going on here? I'm wondering if maybe they weren't drowning in the shell because they were larger? Other eggs in the same batch would do just fine, give or take the usual duds that don't make it.