Menopause and Sexual Functioning: A Review of the Population-Based Studies, The

Sexual problems are among the most frequently presented health concerns of women attending menopause clinics. We examine rigorous observational studies of the menopausal transition to determine whether there are changes in sexual functioning associated with the menopausal transition and the relative roles of aging and hormonal factors. We detail the methodological limitations of menopause research. We then review studies documenting the effects of aging on women's sexual functioning prior to reviewing studies that document both aging and menopausal status. These latter studies are divided into both cross-- sectional and longitudinal studies. In summary, there is an age-related decline in sexual functioning but an added incremental decline associated with the menopausal transition. There have been relatively few studies that have been prospective, population-based, utilised a validated measure of sexual functioning, and carried out concurrent hormonal sampling. The Melbourne Women's Midlife Health Project is a prospective, observational study of a community-- based sample of Australian born women aged 45-55 at baseline. There were eight annual assessments using a self-report questionnaire based on the McCoy Female Sexuality Questionnaire and blood sampling for hormone levels. From early to late menopausal transition, the percentage of women with scores indicating sexual dysfunction rose from 42% to 88%. Decreasing scores correlated with decreasing estradiol but not with androgens. By the postmenopausal phase there was a significant decline in sexual arousal and interest, frequency of sexual activities, and the Total Score. There was a significant increase in vaginal dryness and dyspareunia and women's reports of their partner's problems in sexual performance. Women with low scores of sexual functioning were more likely to be distressed on the Female Sexual Distress Scale. In conclusion, there is a dramatic decline in female sexual functioning with the natural menopausal transition.

Key Words: aging, estradiol, female sexual dysfunction, hormones, menopause, sexuality.

The research issue addressed in this review is the relationship of the menopausal transition and underlying hormonal changes to female sexual functioning. Clinicians have long been concerned about the effect of menopause on female sexual functioning as sexual complaints are amongst the most frequently reported health concerns by women attending menopause clinics (Sarrel & Whitehead, 1985). This indicates that menopausal status (and underlying hormonal change) may be linked to adverse effects on sexuality. Clinical experience, however, is known to be based on a small proportion of self-selecting women who may not be representative of most women's experience (Morse et al., 1994). There are a number of other possible explanations for deteriorating sexual functioning at this phase of life. Major confounders include length of relationship, chronologic aging, other physical health problems, loss of partner, partner's health and medication usage, and the many psychosocial stressors associated with midlife.

Research strategies include those of surveys and clinical trials. Surveys can provide information on the prevalence and types of sexual complaints and the relationship to menopause and other possible determinants. Clinical trials provide evidence of hormonal effects on specific parameters of sexual functioning in the groups studied. These methods are complimentary but have limitations.

Population-based studies enable the study of women in their own naturalistic setting. These investigations also allow assessment of the effect of factors other than hormonal change. The results are then generalisable to the ethnic group and location studied. In evaluating cohort studies, determine the derivation of the sample (look for a randomized sampling technique rather than a convenience sample such as a clinic sample) and sample size. In studies with large sample sizes, often fewer questions are asked, with less assurance of a reliable answer, than in smaller studies, in which investigators may be able to collect more detailed data. Based on our own experience of longitudinal studies of changes in health outcomes with the menopausal transition (see Dennerstein, Lehert, Dudley, & Guthrie, 2001), a minimum of 400 subjects are needed at the outset to provide enough power to detect change. The age of subjects at baseline should be young enough so that measures are obtained before major change in hypothalamic-pituitary-ovarian axis. During the study, documentation is needed of the use of any hormonal therapies (including hormonal replacement therapy [HRT] and oral contraceptives) and of surgery, such as hysterectomy, which may compromise ovarian functioning. Also crucial to the inferences that can be drawn are the type of study (cross-sectional vs. longitudinal), use of validated measures, and statistical techniques that can unravel the complex interrelationships between outcomes and determinants.