The menopausal transition can be viewed in two stages, says a National Institute on Aging-funded consortium:

  • An early transition stage, which begins when menstrual cycle length begins to fluctuate by seven or more days from cycle to cycle.

  • A late transition stage, which begins when women over age 40 first experience a cycle of 60 days or more. Once a woman enters this stage, the median time to her final period is from two-and-a-half to three-and-a-half years. (For women age 45 and younger, other factors such as stress can produce periods of amenorrhea, so younger women should wait to observe a second long cycle of at least 60 days.)

This two-stage categorization of menopause is based on data analyzed by the NIA-funded ReSTAGE project, which includes collaborators heading large-scale, prospective studies of menopausal women. Based on their analysis of longitudinal data on 3,500 women, the ReSTAGE team published recommendations in 2007 for a set of universal criteria to define the menopausal transition, outlined in an article in Climacteric (Vol. 10, No. 2).

Physicians and other clinicians are starting to incorporate these findings into their practices. The researchers hope the categorization will help women better understand and have control over a time of physical flux and uncertainty.

“We want to give women information that will help them identify where they may be in terms of the stage of reproductive aging, so they can make informed choices about contraception and health interventions and have a sense of the changes they can expect,” says University of Michigan epidemiologist Siobán Harlow, PhD, principal investigator of ReSTAGE.

Symptom patterns

Researchers are also examining the relationship between symptoms and hormonal patterns. University of Pennsylvania Research Professor Ellen Freeman, PhD, who heads the university’s Ovarian Aging Study, for example, is in her 14th year of a 15-year study of the menopausal transition funded by the National Institutes of Health. In a cohort of 436 African- American and white women who began the study at ages 35 to 47, Freeman has shown that many symptoms associated with menopause are connected to hormonal patterns, and that each symptom has its own trajectory.

In a 2007 paper in Obstetrics and Gynecology (Vol. 110, No. 2), for instance, Freeman reports that hot flashes, body aches, joint pain and stiffness happen early in the menopausal transition and continue past menopause. By contrast, depressive symptoms tend to increase during the transition, then decrease after menopause. These symptoms are independently related to three factors: fluctuations in estradiol; decreased levels of inhibin, an ovarian hormone that suppresses folicle-stimulating hormone; and increased levels of FSH. This indicates that some symptoms of midlife women are linked to changing reproductive hormones, says Freeman.

Meanwhile, in a 2008 article in Obstetrics and Gynecology (Vol. 111, No 1), Freeman and colleagues reported that headaches peak in the late premenopausal stage when cycle lengths may become shorter or longer. Headaches then decrease throughout the menopausal transition. Mood swings, too, decline significantly from pre- to postmenopause, the team found. Freeman also has found that increased FSH, decreased inhibin and smoking strongly predict when menopause will begin (Menopause, Vol. 16, No. 6).

Some symptoms that are typically associated with menopause — decreased libido, vaginal dryness and sleep problems — do not appear to be associated with hormonal changes in the menopausal transition, at least in this cohort of generally healthy women, Freeman says.

“These findings suggest that for these symptoms, other factors besides ovarian-related hormonal changes are probably at play, such as lifestyle and relationship factors, stress and other physical conditions,” she says.

The importance of ethnicity

While the ReSTAGE researchers didn’t find ethnic differences in the two phases categorizing the menopausal transition, others are zeroing in on symptom differences among ethnic groups with the aim of improving health-care delivery. In Freeman’s sample, for instance, African-American women were more likely than white women to report hot flashes, aches and depression during the transition. Similarly, an ongoing longitudinal study of 3,302 African-American, Japanese-American, Chinese-American and Hispanic women funded by the National Institutes of Health, called the Study of Women’s Health Across the Nation found that African- American women and Hispanic women reported more hot flashes and night sweats than the other groups, while Japanese-American and Chinese-American women reported fewer hot flashes but more body aches.

That said, African-American women had more positive attitudes toward the menopause than the four other groups. In community interviews, the team gleaned possible reasons why: The African-American women said they’d experienced much worse difficulties than menopause — such as racism — and reported spending a lot of time with older female relatives, who gave them a more realistic view of the transition.

The team also found relationships between reported symptoms, ethnicity and physical factors. African-American women, for instance, who reported the highest rates of hot flashes, also had the highest overall body mass index. Meanwhile, African-American and Hispanic women were more likely than others to have had premature menopause or hysterectomies, both of which are associated with more severe symptoms, according to a February 2009 article in Menopausal Medicine (Vol. 17, No. 1).

While these data can help medical practitioners assess symptoms and determine treatment, they shouldn’t be interpreted to mean that ethnicity determines symptom type and severity, the authors caution. What’s behind these differences? It could be genetic factors, sociological factors (including discrimination, education and cultural mores) and physical covariates, such as higher BMI.

Similarly, a pilot study of 158 women reported in 2009 in Health Care for Women International (Vol. 30, No. 4) by University of Texas at Austin nursing professor Eun-Ok Im, PhD, shows strong differences in reported type and severity of some symptoms among white, African-American, Asian- American or Hispanic women. The study also finds that symptom type and severity are associated with such factors as religion, education and income. Im is now exploring these factors in a larger study, funded by NIH, NIA and the National Institute of Nursing Research. She hopes her research will shed more light on these associations and will eventually lead to developing a Web-based menopausal symptom management program for women.

The research will also help health-care practitioners better target services for menopausal women, Im adds.

“The system can’t adequately or appropriately assess and provide for women’s health-care needs without knowing the ethnic-specific contexts around their symptom experience,” she says.

Tori DeAngelis is a writer in Syracuse, N.Y.