[Spontaneous platelet aggregation associated with administration of sex hormones in men and women (author's transl)].

Spontaneous platelet aggregation was measured by an identical rheological method in 19 women and 17 men. Eight of the women (average age 26 years, range 19-56) were at the time on oral contraceptives (group A), the other eleven (average age 26, range 19-50 years) served as controls (group B), as did 17 men (group C) of similar age (average 28, range 22-50 years). Mean maximal aggregation amplitude was significantly greater in group A than B and C (P less than 0.05 and less than 0.025, respectively), which makes it probable that there was a greater tendency to aggregation of the blood platelets under the influence of the oral contraceptive.