Post-menopausal women who use estrogens generally experience at once a reduced risk of coronary heart disease and, at the same time, an increased risk of endometrial cancer. In order to protect the endometrium from unopposed estrogens, many physicians now recommend the addition of a progestin during 10-13 days of the cycle. Progestins may be implicated in the increased risk of myocardial infarction in women on oral contraceptives.