Estrogens failure rate

Like all women, older women who take oral contraceptives should take an oral contraceptive that contains the least amount of estrogen and progestin that is compatible with a low failure rate and individual patient needs. 

Xenobiotic induced disruption of female fertility follows essentially the same pattern as that of the male and can be caused by changes in pituitary-hypothalamic function, primary disruption of ovarian structure or hormone secretion, or changes in the rate of hormone deactivation. In addition, there may be changes in the synthesis of estrogen induced production of the yolk protein by the liver (vitellogenesis), which in turn can lead to failure to lay down sufficient yolk in the developing oocytes. Vitellogenesis provides a valuable biomarker for endocrine dysfunction in both sexes,but is more properly considered as part of the liver function. 

Before discussing the clinical application of these steroidal agents it is well to keep in mind the extraordinary efficacy of this mode of contraception. In Table I we present the data assembled by Venning (31) on the relative efficacy of various contraceptive methods. All of those studied in various experimental trials effectively reduced fertility, but the oral contraceptive most extensively studied (the norethynodrel-estrogen combination) is much the most effective. Indeed, the pregnancy rate listed appears to be attributable to failure to use the method properly rather than to a rare physiological exception to the action of the drug. 

Due to the failure to respond of approximately 40% of patients who were positive for cytosolic ERP and the response of 10% of patients who were negative to ERP (C4, H4), it was accepted that if the results were accompanied by PRP the predictive value would increase (Dl). Another attempt to improve the predictive value of cytosolic ERP was the measurement of nuclear estrogen receptors in addition to the cytosolic ERP (LI). It was found that mixed combinations, whether cytosolic ERP+ nuclear- or cytosolic ERP- nuclear+, correlated with response rates of only 24 and 11%, respectively. 

---