The menstrual cycle is a monthly process where the uterus prepares for potential pregnancy. If fertilization does not occur, the uterine lining sheds, resulting in menstruation, or a period, which typically lasts between two and seven days. Normal total blood loss ranges from 5 to 80 milliliters, or up to six tablespoons. While flow naturally varies throughout the reproductive years, significant increases are usually tied to specific hormonal shifts or developing medical conditions, not a straightforward aging process.
The Relationship Between Age and Menstrual Flow
In the decades following adolescence, particularly the 20s and early 30s, the menstrual cycle generally settles into its most consistent and predictable rhythm. Cycles become more regular, often averaging close to 28 days, and the flow establishes a baseline for what is considered normal for that person.
Changes in flow or cycle regularity during these years are usually influenced by external factors, such as hormonal contraception, lifestyle changes, or pregnancy. Although egg quality declines in the late 30s, this change initially affects fertility more than menstrual flow. The consistency of the cycle remains relatively stable until the hormonal transition into later reproductive life begins.
Hormonal Shifts in Perimenopause and Flow Changes
The most common time for periods to become heavier is during perimenopause, the transition period leading up to menopause. This phase typically begins in the 40s but can start in the late 30s. The primary cause of increased flow is fluctuating hormone levels, specifically the balance between estrogen and progesterone.
As ovarian function declines, cycles often become anovulatory, meaning an egg is not released. When ovulation does not occur, the corpus luteum fails to form, resulting in inadequate progesterone production. Progesterone stabilizes the uterine lining and signals it to shed in an organized manner.
Without progesterone, the uterine lining (endometrium) is continuously stimulated by estrogen, causing it to build up excessively. This unopposed estrogen stimulation results in a thicker, unstable lining. When the lining finally sheds, the volume of tissue and blood loss is significantly greater and often more prolonged, leading to a heavier period.
Common Structural and Medical Causes of Heavy Bleeding
While hormonal shifts account for many age-related flow changes, newly heavy or prolonged bleeding can also stem from physical changes in the uterus. Uterine fibroids, which are benign muscle tumors growing in the wall of the uterus, are a common cause of increased bleeding. They can distort the uterine cavity or interfere with the uterus’s ability to contract and control blood loss.
Endometrial polyps, non-cancerous growths of the uterine lining, are another common cause. These polyps can cause irregular or heavy bleeding, and their incidence increases with age, peaking around age 50. Adenomyosis, where endometrial-like tissue grows into the muscular wall of the uterus, is frequently diagnosed in people in their 30s and 40s. This condition causes the uterus to become enlarged and tender, leading to painful and heavy bleeding.
Identifying Abnormally Heavy Bleeding and When to Consult a Doctor
Heavy menstrual bleeding, medically termed menorrhagia, is defined by specific criteria that exceed a person’s typical flow. You should suspect abnormally heavy bleeding if you soak through one or more sanitary pads or tampons every hour for several consecutive hours. Other indicators include needing to double up on protection, passing blood clots larger than a quarter, or having a period that lasts longer than seven days.
Chronic heavy bleeding can lead to anemia, a condition resulting from insufficient red blood cells. Symptoms of anemia include persistent fatigue, weakness, or shortness of breath, which warrant a medical checkup. Consult a healthcare provider if you experience a sudden change from your usual pattern, or if you have any bleeding between periods or after sexual activity. Seeking medical evaluation is necessary to rule out non-hormonal causes and ensure proper diagnosis and treatment.