Changing Length of Menstrual Period Normal During Perimenopause

Dorian Martin Health Guide
  • Sometimes women don’t realize that their bodies are undergoing and they’re in the throes of perimenopause until they start experiencing differences in the timing of their menstrual period.  One time it lasts for almost weeks. At another time, their monthly period may continue for only three days, while the next one might last for six days. However, it turns out that what women might deem as “unusual” periods are not really that far out of the norm for this stage of life.


    A new study out of the University of Michigan’s School of Public Health and University of Michigan Health System explored the issue of irregular bleeding episodes during perimenopause. The study involved 1,320 women between the ages of 42 and 52 who were participants in the Study of Women’s Health Across the Nation (SWAN) Menstrual Calendar Substudy. These participants included African-American, Chinese, Japanese and white women.

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    The researchers asked study participants to complete daily menstrual calendars over the decade from 1996 until 2006. The participants were also asked to share information on their physical activity levels, smoking and any hormone therapy that they were taking.  The researchers also recorded each participant’s height and weight annually.


    The researchers’ analysis found that changes in menstrual periods happened to many women during this time frame. For instance, 91 percent of the study participants had between 1-3 episodes of bleeding that lasted 10 or more days during a three-year period while 77 percent had at least three occurrences of periods of this length during the study period. Almost 88 percent of participants reported having six or more days of spotting during a three-year period; approximately 67 percent reported having at least three occurrences of six or more days of spotting during the course of the study. Nearly 78 percent of the study participants reported three or more days of heavy bleeding during a three-year period while almost 35 percent reported having three heavy bleeding episodes for three or more days during the course of the study. The researchers found that these three types of bleeding were associated with the menopausal transition, uterine fibroids, hormone use and ethnicity. Furthermore, body mass index was linked to having more than three days of heaving bleeding.


    These patterns go counter to what many women have experienced previously during their lives. "For most women in their 30s, menstrual periods are highly predictable. With the onset of the menopausal transition in their 40s, women's menstrual periods can change dramatically. These dramatic changes can be disconcerting and often provoke questions about whether something is wrong," said Dr. Sioban Harlow, a U-M professor of epidemiology who coauthored the study. “Women need more descriptive information about the bleeding changes they can expect. We need clear guidance to help women understand what changes in bleeding patterns do and do not require medical attention."


  • While this news is good in many ways, you do need to proceed with caution in certain instances. “This news can be reassuring, but it doesn’t mean you should keep quiet about noticeable bleeding changes, especially if you are overweight,” said Dr. Margery Gass, the executive director of the North American Menopause Society. “Overweight women have a higher risk of uterine cancer (called endometrial cancer), and frequent or heavy bleeding can be a sign of cancer for any woman. Note also that the study said three long periods occurring over three years. If a woman is experiencing heavier and/or longer periods every month or bleeding frequently throughout the month, that should also be reported to your healthcare provider sooner rather than later.”

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    Primary Sources for This Sharepost:


    Gass, M. (2014). Long or heavy periods not uncommon in your 40s, but… The North American Menopause Society.


    Paramsothy, P., et al. (2014). Bleeding patterns during the menopausal transition in the multi-ethnic Study of Women’s Health Across the Nation (SWAN): a prospective cohort study. BJOG.


    University of Michigan. (2014). Prolonged and heavy bleeding during menopause is common.

Published On: April 22, 2014