Perimenopause is the body’s natural transition period leading up to menopause, defined as twelve consecutive months without a menstrual period. This phase typically begins in a person’s 40s, though it can start earlier or later, and is characterized by a significant shift in reproductive hormones. As the ovaries gradually slow their function, the menstrual cycle often becomes unpredictable, changing both the interval between periods and the duration and amount of bleeding. These fluctuations are the primary reason why periods can become noticeably longer and heavier during this stage of life, affecting up to 90% of women in the mid-to-late perimenopausal years.
How Hormonal Shifts Lengthen Menstrual Bleeding
The lengthening of menstrual periods in perimenopause is directly related to the unpredictable changes in the two main reproductive hormones: estrogen and progesterone. During the years leading up to menopause, the process of ovulation, where an egg is released from the ovary, becomes less frequent and more erratic. When ovulation does not occur, the cycle is called anovulatory, and this disrupts the normal hormonal sequence.
Normally, after ovulation, the empty follicle transforms into the corpus luteum, which produces progesterone. Progesterone’s primary role is to mature and stabilize the uterine lining, or endometrium, preparing it for a potential pregnancy. If an egg is not released, the body does not produce the expected amount of progesterone.
This lack of progesterone leaves the endometrium exposed to the continuous, often fluctuating, influence of estrogen. Estrogen stimulates the growth of the uterine lining, causing it to build up and become excessively thick because the stabilizing effect of progesterone is absent. This condition is sometimes referred to as relative estrogen dominance.
When the body finally sheds this overgrown, unstable lining, the bleeding episode is often significantly heavier and lasts longer than a typical period. The prolonged shedding of the thick endometrium can extend the bleeding duration to well over a week, instead of the regular three-to-seven-day period.
When Extended Bleeding May Signal Other Issues
While hormonal shifts commonly explain prolonged bleeding in perimenopause, extended or excessively heavy bleeding requires medical evaluation to rule out other possible causes. Bleeding that lasts longer than seven days, or that is so heavy it requires changing a pad or tampon every hour for several consecutive hours, should be investigated by a healthcare provider. Bleeding that occurs between periods also warrants a clinical assessment.
Several non-perimenopausal conditions can mimic or exacerbate changes in menstrual bleeding. Uterine fibroids, non-cancerous growths in the muscular wall of the uterus, and endometrial polyps, overgrowths of the uterine lining, can both cause heavy, prolonged, or irregular bleeding episodes. Both fibroids and polyps become more common as people age.
Other systemic conditions can also impact the menstrual cycle. These include thyroid disorders, particularly hypothyroidism, which can disrupt hormonal balance and contribute to heavy bleeding. Bleeding disorders, such as von Willebrand disease, which impairs the blood’s ability to clot, may also first present or worsen with age, leading to heavy bleeding.
Of serious concern is the possibility of endometrial hyperplasia, an excessive thickening of the uterine lining, or in rare cases, endometrial cancer. The unopposed estrogen responsible for perimenopausal bleeding can increase the risk for these conditions. Consulting a medical professional ensures the cause of the prolonged bleeding is accurately identified, allowing for appropriate management.
Strategies for Managing Heavy and Long Periods
Once a medical evaluation confirms that prolonged bleeding is related to perimenopausal hormonal changes, several strategies can help manage the symptoms. For immediate relief from heavy flow, over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen can be taken during the period. These medications reduce blood loss by inhibiting the production of prostaglandins, compounds that trigger uterine contractions and bleeding.
Non-hormonal prescription options, such as tranexamic acid, are also effective. This medication works by promoting blood clotting, which helps to slow the flow during the heaviest days of the period. For those experiencing fatigue from chronic blood loss, iron supplementation may be necessary to prevent iron-deficiency anemia.
Hormonal treatments directly address the underlying imbalance and regulate the cycle. Low-dose oral contraceptives containing both estrogen and progestin can regulate periods and reduce blood flow by up to 40%. A highly effective long-term option is a levonorgestrel-releasing intrauterine device (IUD). The IUD releases a progestin hormone directly into the uterus, significantly thinning the lining and resulting in much lighter, or even absent, periods.