Does cigarette smoking alter platelet aggregation in women receiving the contraceptive pill?

Platelet aggregation was examined in a group of 35 nonsmokers and 15 smokers who were receiving oral contraceptives (OC; 30 mcg ethinyl estradiol and norgestrel or norethisterone). Platelet aggregation induced by ATP was greater after 4-6 months' use of OCs in both groups, and there was no difference between the 2 groups. The increased risk of thromboembolic in smokers on OCs would appear to be unrelated to the effects on platelets.