C. Jamin et al., The role of selective prescribing in the increased risk of VTE associated with third-generation oral contraceptives, HUM REP UPD, 5(6), 1999, pp. 664-671
In the early 1960s, it became apparent that oral contraception (OC) with oe
stroprogestogens increased the cardiovascular, venous thromboembolic (VTE),
myocardial infarction (MI) and cerebrovascular accident (CVA) risk. The ch
ange in medical prescribing patterns, the reduction in ethinyloestradiol do
sage and the use of less androgenic progestogens made prescribers confident
that the risks would subsequently decrease. At the end of 1995 and early 1
996, four publications called into question that optimism by showing that t
hird-generation pills induced a two-fold increase in VTE risk compared with
second-generation pills. A biological rationale was due to be announced la
ter. Since then, re-analysis of the data has shown that the thrombotic risk
factors are increased in third-generation OC users but, more importantly,
that those users (unlike those using second-generation pills) are the women
who have not had the opportunity of revealing a latent thrombophilia and a
re, therefore, at a greater risk of expressing it during third-generation O
C intake. When these data are considered, the difference between second- an
d third-generation OC users in terms of VTE risk is completely destroyed. I
n addition and although the risk factors (smoking in particular) are concen
trated in third-generation OC users, the MI risk is less in those users tha
n in second-generation Dill users. This is particularly true in the presenc
e of a risk factor such as smoking, No difference in risk has been observed
for CVA in the general population between second- and third-generation OC
users, but once more among smoking women the risk is lower with third-gener
ation OC.