Frequent Menstruation: Why Your Period Comes Too Often

What counts as frequent menstruation

A typical menstrual cycle is 24 to 38 days long. Count from the first day of bleeding to the day before the next period starts. Under the FIGO system that gynecologists use, a cycle shorter than 24 days is called frequent menstrual bleeding. The traditional term, polymenorrhea, is still widely used.

It is important to tell true frequent periods from bleeding between periods. Frequent periods are full periods that come too often. Intermenstrual bleeding is spotting or bleeding between otherwise regular periods, which has different causes such as polyps or infections.

A cycle-tracking app or calendar for 3 months makes the pattern clear.

Causes of frequent periods

Hormonal causes

• Teen years: in the first 2 to 3 years after periods start, the hormonal system is still maturing and cycles can be short, long or irregular.
• Perimenopause: in your 40s, a shorter follicular phase often shortens cycles to 21 to 24 days before they become longer and irregular. This is one of the commonest causes in adults.
• Short luteal phase: the second half of the cycle, after ovulation, is less than about 10 days, often from lower progesterone.
• Thyroid disease: both an overactive thyroid (hyperthyroidism) and an underactive one can change cycle length.
• Stress, intense exercise, weight change and illness can disrupt the hormonal signals from the brain.

Medicines and contraception

• Starting, stopping or missing doses of hormonal contraception
• Emergency contraception, which can bring the next period early
• Blood thinners, which can make bleeding seem more frequent or prolonged

Structural and other causes

• Uterine fibroids and endometrial polyps: more often cause heavy or irregular bleeding, which can be mistaken for frequent periods.
• Endometriosis: associated with shorter cycles and painful periods.
• Pelvic inflammatory disease: infection causing irregular bleeding, pain and discharge.
• Endometrial hyperplasia or cancer: a less common cause, mainly over 45.

Why frequent periods matter

• Iron deficiency: losing blood every 2 to 3 weeks can drain iron stores, causing tiredness, breathlessness, hair thinning and iron deficiency anemia.
• Fertility: a very short cycle may mean ovulation is not happening or the luteal phase is too short for implantation.
• Quality of life: more days of bleeding, cramps and PMS.

How doctors find the cause

A doctor will ask about your cycle pattern, bleeding heaviness, pain, contraception, sexual history, stress, weight and other symptoms. Typical tests include:

• pregnancy test
• complete blood count and ferritin
• thyroid function
• sometimes FSH, prolactin and other hormones, timed to your cycle
• sexually transmitted infection testing
• a transvaginal ultrasound to look for fibroids, polyps and lining thickness
• an endometrial biopsy if you are over 45 or have risk factors

Treatment

Treatment depends on the cause, how much the bleeding bothers you, and whether you want to become pregnant.

• Hormonal contraception: the combined pill, patch or ring, or a hormonal IUD, can regulate and lighten periods.
• Progestin therapy for a short luteal phase or perimenopausal irregularity.
• Treating thyroid disease usually normalizes cycles.
• Iron supplements for low iron.
• Antibiotics for pelvic infection.
• Removing polyps or fibroids if they are the cause.
• Lifestyle: managing stress, regular sleep, and avoiding extreme dieting or overtraining.

Frequently asked questions

Is it normal to have your period twice a month?

Occasionally, yes. A cycle of 21 to 24 days can mean two periods fall in one calendar month. Cycles shorter than 24 days that keep happening are considered frequent menstruation and should be checked, especially with heavy bleeding or tiredness.

What causes frequent menstruation?

Common causes are hormonal changes in the teen years and perimenopause, stress, thyroid problems, changes in contraception, a short luteal phase, fibroids, polyps, endometriosis and pelvic infection. A doctor can find the cause with simple tests.

Can stress make your period come early?

Yes. Stress affects the brain's hormone signals that control ovulation, which can shorten or lengthen a cycle. A single early period after a stressful time is common. Repeated short cycles need medical evaluation to rule out other causes.

Does frequent menstruation affect fertility?

It can. Very short cycles may mean ovulation is not occurring or the luteal phase is too short for an embryo to implant. Many people with slightly short cycles conceive normally. See a doctor if you have been trying for 12 months, or 6 months if over 35.