[The role of age, smoking habits, and oral contraceptives in the frequency of myocardial infarction in young women (author's transl)].

Owing to the discussion aroused by different papers which have appeared in the last few years on the possible side-effects of oral contraceptives, an examination is made in this paper of the methods used in some of these studies, trying to elucidate to what extent we can trust the conclusions obtained, in order to decide whether oral contraceptives, by themselves, are a real and considerable risk to women's health, and analysing the role of oral contraceptives associated with other risk factors which can influence the frequency of myocardial infarction in young women. It is concluded that the use of oral contraceptives does not represent a statistically significant risk and, therefore, a causal inference cannot be attributed to them; but there exist other risk factors which prove to be of statistically demonstrable danger for myocardial infarction, such as smoking and obesity. Also, it seems evident that the combined effect of smoking and oral contraceptive use is synergistic. However, even though these two factors associated can increase the risk of myocardial infarction, we must not dismiss the possibility of this increment being influenced by other, equally logical circumstances.