Longitudinal Studies of Perimenopause: 5 Key Studies

Longitudinal studies of perimenopause (aka the menopausal transition) are key to really understanding this life phase.

Longitudinal research studies a group of people over a long period. Several groups of investigators have studied the menopausal transition in this way.

• However, the majority of these studies only began in the 90s — the 1990s!
• There wasn’t a women’s health agenda at the National Institute of Health until 1991.¹ At this point, women began to ask for a way to know where they were in the process we call the menopausal transition, as well as when menopause, was going to occur.

We created the figure below to be able to map the key longitudinal studies of perimenopause. These studies that aimed to establish the stages a person progresses through on the path to menopause, the final menstrual period.

LONG-TERM STUDIES OF THE PATH TO MENOPAUSE

MT= Menopause Transition, FMP=Final Menstrual Period

Notice 4 things as you look at this figure of longitudinal studies of perimenopause:

1. Each study used a slightly different framework for how to describe where someone was in the transition.

• This makes it difficult to use information from multiple studies to understand one particular phase.
• This is one reason why a clearer picture of what women experience during this normal transition is not recognized.

2. Of these studies, only three began at age 35 or before

• The 3 that did were; The Seattle Midlife Women’s Study (SMWHS), the Penn Ovarian Aging Study (POAS) and The Freedom Study.
• The others listed here and most other studies of this phase started with women at 47 and a few at 45.
• The reason for this is that the focus of menopause researchers has been on the final menstrual period (i.e. menopause).
• Long studies are expensive so starting at 35 and ontinuing until 51, the average age at menopause, is costly.
• The downside of this is that not much is known about the earliest changes on the journey to menopause as women enter their late 30s when their fertility is waning and hormonal patterns are changing for some.

3. It wasn’t until 2001 that a global group of investigators convened to create a single framework to direct future research.

• Many of the researchers who conducted these longitudinal studies of perimenopause were included.
• That effort was called Staging Reproductive Aging Workshop (STRAW) and we have added it to the figure as well (shaded in grey).
• You’ll note that even some subsequent studies have not used the framework.

4. STRAW stipulates that a difference of 7 days between consecutive cycles has to happen 2 times in 10 cycles before you enter the Menopausal Transition (aka perimenopause).

• As an example, this is a 35-day cycle followed by a 28-day cycle.
• This is why our healthcare providers didn’t think to suggest that our new experiences with sleep and mood might be related to the start of the many-years menopause transition. We now know that it was!
• In the STRAW framework, the phase before the Menopausal Transition is called the Late Reproductive Stage (LRS). Creating more awareness through research and education is the mission of our work at Women Living Better.
• As part of our research collaboration with Dr. Nancy Woods, Dr. Marcie Richardson and Dr. Ellen Mitchell we have conducted a Scoping Review to gather all of the research that has been done on the LRS — the time when women are having regular cycles but subtle change to cycle length, days of flow or amount of flow have begun.

This very thorough review of previous research efforts confirmed our early, more cursory review, that not much is known about the earliest part of the menopause transition.