The luteal phase is the part of your menstrual cycle that occurs after ovulation, but before the first day of your next menstrual cycle. It typically lasts between 10 to 14 days. Sometimes, women with fertility problems have a short luteal phase, which has also been connected to recurrent miscarriages.
What Happens During the Luteal Phase?
The luteal phase prepares the endometrium and body for pregnancy. Your body assumes that the egg that was ovulated during the follicular phase has been fertilized, so the follicle that released the egg becomes a corpus luteum. This secretes estrogen and progesterone. Progesterone does the following things:
- Suppresses the hormones GnRH, FSH, and LH: hormones that stimulate the ovaries and cause ovulation. Otherwise, you might conceive again after you already were pregnant.
- Prepares the endometrium: progesterone triggers the uterine lining (or endometrium) to secrete special proteins, which will nourish an embryo.
- Prevents menstruation: progesterone stops the endometrium from breaking down, which could lead to miscarriage if you’re pregnant.
Progesterone is also responsible for luteal phase symptoms, which are often confused for early pregnancy signs.
How Long Should It Be?
It typically lasts between 10 and 14 days, but can be as short as 8 days or as long as 16 days. Your regular phase length should be consistent each cycle. If it lasts longer than usual, it may be an early sign of pregnancy. If it is shorter than 8-10 days, it may be a sign of a fertility problem. However, it is possible for women to have a short luteal phase and still have good fertility.
Luteal Phase Defect
A luteal phase defect is defined as having low or inadequate levels of progesterone during the luteal phase, and is considered a theoretical cause of infertility and early miscarriage. Some symptoms of a defect can include spotting between ovulation and your expected period, short menstrual cycles, irregular ovulation or anovulation, and repeated early miscarriage.
With IVF treatment, progesterone supplementation has been shown to improve the luteal phase and improve pregnancy outcomes.
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