Cigarette smoking and pregnancy II: vascular effects.

The act of smoking introduces a complex set of chemicals that have a broad range of effects, both complementary and antagonistic, at various levels within the vascular tree. A general review of these systemic effects is followed by a summary of documented effects of smoking on the uterine vasculature and of relationships of smoking to pregnancy outcomes known to be associated with vascular pathology. Last, we offer a potential resolution for the apparent paradox of the seemingly 'protective' effect of smoking to reduce the incidence of pre-eclampsia, one of the most serious vascular complications of pregnancy.