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Luteal Phase Defect

A luteal phase defect is a disruption in a woman's monthly menstrual cycle.

The luteal phase is one stage of the menstrual cycle. It occurs after ovulation (when the ovaries release an egg) and before your period starts.

During this phase, the lining of your uterus normally becomes thicker to prepare for a possible pregnancy.

If you have a luteal phase defect, the lining of your uterus does not grow properly each month. This can make it difficult to become or remain pregnant. However, persistent luteal phase defect has not been proven to be a direct cause of infertility.

A luteal phase defect may also be called an "inadequate luteal phase" or an abnormality in endometrial development.


Female Reproductive System

Causes of Luteal Phase Defect

The luteal phase is usually about 12 to14 days long. During this time, your ovaries produce a hormone called progesterone. This hormone tells the lining of the uterus, called the endometrium, to grow.

If you become pregnant, the developing baby attaches to this thickened lining. If you do not become pregnant, the lining eventually sheds, and you have a period.

A luteal phase defect can occur if:

  • Your ovaries do not release enough progesterone.
  • The lining of the uterus does not properly respond to the progesterone.

Luteal phase defect has been linked to many health conditions, including:

  • Anorexia
  • Endometriosis
  • Extreme amounts of exercise
  • Hyperprolactinemia (excess of a hormone that's responsible for milk production in breasts)
  • Obesity
  • Polycystic ovarian syndrome
  • Thyroid disorders

Luteal Phase Defect Symptoms

You may not have any symptoms or notice any changes in your period. However, a luteal phase defect can cause your period to start earlier than expected each month.

Symptoms of luteal phase defect may include:

  • More frequent periods
  • Miscarriage
  • Difficulty getting pregnant
  • Spotting in between periods

Diagnosing Luteal Phase Defect

It may be difficult to diagnose a luteal phase defect. There is no single test that can diagnose it.

Blood tests that can be helpful include:

  • Follicle-stimulating hormone (FSH) level
  • Luteinizing hormone (LH) level
  • Pregnancy test
  • Progesterone level

Some doctors recommend a series of endometrial biopsies. This checks the lining of the uterus. A small sample of this lining is removed at a specific time of the month and examined under a microscope.

The biopsy is usually done a day or two before you think you will get your period. A pregnancy test should be done before an endometrial biopsy is done. You should not have an endometrial biopsy if you are pregnant.  

An endometrial biopsy can help your doctor determine if you are "in phase" or not.  A definitive diagnosis is based on two or more "out of phase" biopsy results.

However, every woman can have luteal phase changes from time to time. The National Institutes of Health says that an endometrial biopsy cannot tell the difference between fertile and infertile women. It does not recommend it as a routine infertility test.

The beta-3 integrin biomarker test is a newer method to help determine if the lining of the uterus is ready for pregnancy. This test is done using a sample of the lining taken during an endometrial biopsy.

Beta-3 integrin is a sticky protein found in the lining of the uterus. If you do not have this protein, the embryo may not properly implant in the lining. This reduces your chances for a successful pregnancy.

Pelvic ultrasound may also help your doctor measure the thickness of the lining.

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