Endometrial responses to hormone replacement therapy: the bleeding pattern

Little information is available concerning the response of the endometrium to exogenous sex steroid therapy, particularly in the post-menopausal state. In this study we examined the variability of the bleeding pattern in 103 post-menopausal women receiving cyclical sequential combined hormone replacement therapy (HRT) over 6 months. All patients kept menstrual diary cards to record the onset, duration and subjective assessment of the severity of bleeding. We defined a cycle as starting from the commencement of treatment till the day of onset of bleeding. Two groups were identified amongst 99 women who experienced bleeding: those with a mean cycle length of 29 or more days (late bleeders, n = 50) and those with shorter mean cycle length (early bleeders, n = 49). The former were characterized by less variability in cycle length and bleeding that was of shorter duration. Four women experienced no bleeding. There were no significant differences between the two groups in age, year since the menopause, weight, height, body mass index (BMI), parity, or in the previous use of HRT. The only significant difference was in their smoking habits. This suggests a possible link of a hypo-oestrogenic state to poor cycle control.