Irregular cycles: when should you worry?

Summary

Cycles are expected to change in perimenopause: first they shorten, then they lengthen, some are skipped, and sometimes bleeding gets heavier. This is the basis of the staging and is not in itself a cause for concern. But the word "perimenopause" can lead to bleeding that needs investigating being brushed aside. Uterine polyps, fibroids, thickening of the lining of the womb and, rarely, cancer are common in this same age group and cause similar symptoms. This article sets out the line between "expected" and "needs investigating"; only your doctor can draw that line for you.

What is happening?

The main reason for irregular bleeding in perimenopause is that ovulation becomes less frequent (see the separate article on progesterone and the cycle). The expected pattern:

• Early perimenopause: A difference of 7 days or more between cycles; some cycles shorten (21-24 days), others lengthen. The amount of bleeding may vary.

• Late perimenopause: Gaps of 60 days or more without a period; the bleeding that follows is sometimes heavier, because the lining of the womb has been exposed to estrogen for a long time.

• Toward the last period: The intervals widen, bleeding becomes lighter and less frequent; the last period can only be identified in hindsight, 12 months later.

Not every irregularity in perimenopause is hormonal. At the same ages, polyps (benign growths on the lining of the womb), fibroids (muscle tumors), adenomyosis, endometrial hyperplasia (excessive thickening of the lining) and, rarely, endometrial cancer cause bleeding. Thyroid disease and clotting disorders can also make bleeding heavier.

What do we know?

• Variability is part of the definition: STRAW+10 defines perimenopause by exactly this variability in cycle length; irregularity in itself is therefore not a sign of disease ¹.

• But there are limits: The international (FIGO) classification defines the following as "abnormal uterine bleeding" requiring assessment: bleeding lasting more than 8 days, irregular intervals shorter than 24 days or longer than 38 days, bleeding between periods, and heavy bleeding that affects your life ².

• The threshold for assessment is low over 45: ACOG recommends taking a sample from the lining of the womb (endometrial biopsy) as first-line assessment in women over 45 with abnormal uterine bleeding; under 45 it recommends it where there is unopposed estrogen exposure (obesity, an ovulation disorder) or no response to treatment ³. Transvaginal ultrasound is the first imaging test for polyps and fibroids.

• Heavy bleeding can be treated: NICE recommends the hormonal intrauterine device (levonorgestrel IUD) as a first-line option for heavy menstrual bleeding; tranexamic acid taken during the period, painkilling/anti-inflammatory medicines, cyclical progestogens and hormonal contraceptives are other options. Where there is a structural cause (a polyp, a fibroid), hysteroscopic or surgical treatment is considered ⁴. Which one is right for you is your doctor's decision.

• Anemia is common and silent: Heavy bleeding leads to iron deficiency and anemia, which show up as fatigue, hair loss and palpitations. A blood count and ferritin are a standard part of assessing heavy bleeding ⁴.

What does this give you?

• Record it: The start and end date of the bleeding, how heavy it was (number of pads/tampons, clots), and any spotting in between. That is what the cycle calendar in Lumia is for; saying "intervals of 22, 41 and 19 days, the last one lasting 9 days" instead of "irregular for three months" answers most of your doctor's first questions.

• Don't settle for "it's perimenopause": If the bleeding is heavy, prolonged, between periods, or affecting your life, ask for an assessment. That usually means a simple ultrasound and, if needed, a short biopsy done in the office.

• You don't have to put up with heavy bleeding: There are effective options, including hormone-free ones.

• Pregnancy is still possible: An irregular cycle does not mean contraception is unnecessary; and a late period should be assessed with a pregnancy test in perimenopause too.

Sources

1. Harlow SD, et al. Executive summary of the Stages of Reproductive Aging Workshop + 10. Menopause. 2012;19(4):387-395.
2. Munro MG, et al. The two FIGO systems for normal and abnormal uterine bleeding symptoms and classification of causes (PALM-COEIN): 2018 revisions. Int J Gynaecol Obstet. 2018;143(3):393-408.
3. ACOG Practice Bulletin No. 128: Diagnosis of abnormal uterine bleeding in reproductive-aged women. Obstet Gynecol. 2012;120(1):197-206.
4. NICE. Heavy menstrual bleeding: assessment and management (NG88). 2018; updated 2021.

Related articles

• Perimenopause, menopause, postmenopause: what do the stages mean? 5 min read
• Progesterone and the cycle: why does it fall first in perimenopause? 5 min read
• Bleeding after menopause 4 min read
• How do hormones change during this period? 5 min read