Endometrial Thickness: The Golden Key to a Healthy Pregnancy or a Uterine Cancer Nightmare?

According to the Family Magazine service of Saed News, the endometrium is the lining of the uterus. It is one of the few organs in the body that changes every month during a person’s reproductive years. Each month, as part of the menstrual cycle, the body prepares the endometrium to host a potential embryo. The thickness of the endometrium fluctuates during this process. Two hormones—estrogen and progesterone—control this growth cycle, and if pregnancy does not occur, the endometrium sheds during menstruation. This article explores the normal range of endometrial thickness, the causes of changes, and when to consult a doctor.

What Is the Normal Thickness of the Endometrium?

Endometrial thickness changes throughout life—from childhood to puberty, through reproductive years, and after menopause. Imaging studies in young girls who have not yet menstruated show an endometrium, though it is smaller than in later stages of life.

During menstruation, the endometrium is at its thinnest, usually measuring 2 to 4 millimeters. In the first half of the menstrual cycle, roughly days 6 to 14—or after bleeding has stopped and before ovulation—the endometrium begins to thicken, reaching 5 to 7 millimeters. As the cycle progresses toward ovulation, it thickens further to about 11 millimeters. Around day 14, hormones trigger the release of an egg, and at this point, endometrial thickness peaks at approximately 16 millimeters.

Endometrial Thickness in Pregnancy

Endometrial thickness is important for pregnancy. Health professionals consider an endometrium that is neither too thin nor too thick as the optimal environment for a successful pregnancy. Adequate thickness allows the embryo to implant properly and receive necessary nourishment. As pregnancy progresses, the endometrium continues to thicken.

Endometrial Thickness After Menopause

In healthy postmenopausal individuals, the endometrium typically measures around 5 millimeters or less.

How Is Endometrial Thickness Measured?

Ultrasound is the most common method for measuring endometrial thickness. It is often the first tool healthcare providers use, especially if someone reports abnormal vaginal bleeding. When ultrasound is not feasible due to uterine position or other medical conditions, magnetic resonance imaging (MRI) may be used.

Causes of Thick or Thin Endometrium

While endometrial thickness naturally changes during the menstrual cycle, other factors can also affect it:

Thickening causes include:

• Pregnancy, including early pregnancy or ectopic pregnancy

• Uterine or ovarian cancer, with endometrial cancer being one of the most common reproductive system cancers. It is rare in women under 45, with the average age of diagnosis at 60

• Obesity

• Hormone therapy

• Tamoxifen use

• Chronic high blood pressure

• Endometrial polyps

• Diabetes

• Scar tissue

• Endometrial hyperplasia, a condition where the endometrium becomes excessively thick, often due to high estrogen levels or insufficient progesterone. Hyperplasia is not cancer but may increase cancer risk

Thin endometrium is usually defined as 7 millimeters or less. Studies show that about 5% of people under 40 and 25% over 40 have thin endometrium. Causes may include inflammation, medical treatments, or intrinsic uterine factors.

Symptoms of Excessive Endometrial Thickness

Common signs include:

• Postmenopausal bleeding

• Very heavy or prolonged menstrual bleeding

• Irregular cycles lasting less than 3 weeks or more than 38 days

• Spotting between periods

Treatment of Thickened Endometrium

Treatment often involves progesterone, the female hormone that regulates ovulation and can prevent further uterine thickening. Studies indicate that excessively thick endometrium can complicate pregnancy progression.

Treatment of Thin Endometrium

Managing a thin endometrium may involve:

• Estrogen therapy

• Human chorionic gonadotropin (hCG), a hormone produced by the placenta after embryo implantation

• Medications or supplements to improve blood flow