Luteal Phase Defect (LPD)

The luteal phase refers to the time in a normal menstrual cycle that begins after ovulation (when a mature egg is released) and continues until the start of your next menstrual period. The average luteal phase lasts for 14 days, but 10 to 16 days is considered normal. The length of the luteal phase varies from woman to woman, although for each individual woman the length is fairly consistent from cycle to cycle.

During the luteal phase, FSH (follicle stimulating hormone) stimulates the production of a follicle in one of your ovaries. The follicle contains a single egg, and in a normal cycle the follicle releases the egg at ovulation. The corpus luteum, which is created from the cells that remain behind after the egg is released, secretes the hormone progesterone which is needed to maintain pregnancy. This rise in progesterone causes the endometrial lining of the uterus to thicken and makes it a receptive environment for the implantation and nurturing of the fertilized egg.

What Is Luteal Phase Defect?

Luteal Phase Defect (LPD) leads to a disruption in progesterone production. You are considered to have a luteal phase defect if your luteal phase lasts fewer than 10 days. Some doctors, however, believe that a luteal phase of less than 12 days indicates LPD.

What Causes LPD?

Problems associated with LPD can occur during different times in your menstrual cycle and in conjunction with each other. You might have poor follicle production or premature failure of the corpus luteum, both of which result in below-normal levels of progesterone. In this instance, your period starts sooner than expected.

On the other hand, you might have normal levels of progesterone, but the lining of your uterus does not respond correctly to it.

How Does LPD Affect Fertility?

If you do not produce enough progesterone, you will be unable to sustain a pregnancy. The endometrial lining of the uterus will break down, which may trigger menstrual bleeding and cause an early miscarriage. If you produce enough progesterone but your uterus does not respond to it, the lining is not adequately prepared or thick enough for the embryo to attach to it.

About 3 percent to 4 percent of women with LPD are infertile and up to 5 percent have a history of repeated miscarriages. However, up to 30 percent of otherwise healthy women also have luteal phase defects.