Luteal phase defect can be associated with recurrent miscarriage
Luteal phase defect is a condition that is associated with recurrent miscarriage and possibly with infertility as well. An ovulatory cycle is divided into two phases.
The part of the cycle prior to ovulation is called the follicular phase. During this time, the follicle (the fluid filled sac within the ovary that contains the oocyte) develops in preparation for release of the oocyte. The developing follicle produces a type of estrogen (“estradiol”), that stimulates growth or thickening of the uterine lining (the “endometrium”).
This estrogen production is also responsible for increasing the cervical mucous production and changing its characteristics to make it more favorable for sperm penetration. When release of the egg occurs (“ovulation”), the cells remaining in the follicle undergo changes that allow them to produce another hormone called progesterone. This process is called “luteinization”, and it is triggered by the release of a hormone called luteinizing hormone, or LH.
Following this LH surge, the follicle changes names and it becomes the “corpus luteum”. This event is the beginning of the luteal phase, which makes up the second half of a woman’s cycle. The progesterone made by the corpus luteum causes changes to occur within the endometrium that make it more favorable for embryo attachment (“implantation”).
If progesterone production is weaker than normal, the endometrium may not develop sufficiently for an embryo to implant. This situation is called a luteal phase defect. The developing endometrium is dependent on adequate progesterone production from the ovary.
The Importance of progesterone in the luteal phase
Although many physicians focus on the blood progesterone level, it is actually more important that progesterone production be of a sufficient quantity for an appropriate number of days. The absolute serum level of the hormone is not as important.
Therefore, simply measuring the serum level may be misleading. It is more accurate to evaluate the effect of progesterone on the endometrium over time. This is accomplished by examining a piece of uterine lining tissue under a microscope, a procedure call an endometrial biopsy. This biopsy is obtained close to the end of the luteal phase, which is the most accurate time to evaluate the luteal phase. Another acceptable (and far less uncomfortable) way of evaluating the luteal phase is to count the number of days from the time of ovulation until the woman begins her next menses. A normal luteal phase needs to be at least 12 days.
Treatment for luteal phase defects, includes progesterone supplementation
The most common treatment for a short luteal phase is to give the woman extra progesterone. Progesterone supplementation can effectively prevent the loss of a pregnancy when given to women with a luteal phase defect. Usually, progesterone supplementation is begun three days following ovulation. It is therefore important to accurately document the day of ovulation, as starting progesterone too soon may increase the risk of a tubal pregnancy. It is common for women to use a urinary ovulation predictor kits to determine the day of ovulation. As the LH surge typically precedes ovulation by 18-30 hours, progesterone supplementation is begun four days after the initial detection of the LH surge.
Types of progesterone supplementation
Supplemental progesterone is given to all women undergoing in vitro fertilization. In the past, intramuscular progesterone was utilized exclusively for IVF supplementation. Recent data, including one of the largest studies on this topic – performed at TFC – suggest that other methods of progesterone supplementation, such as a vaginal gel, are just as effective, if not more so.
Oral progesterone is not as effective because of its short half life, and also because it may be broken down by stomach acid. When a medication has a short half life, it needs to be given more frequently to maintain adequate levels in the circulation. Luteal phase defect is a significant cause of recurrent miscarriage – and possible infertility as well – that, once diagnosed, is easily treatable.
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