Recurrent Pregnancy Loss - An Overview
While the strict medical definition of recurrent pregnancy loss states that there must be three consecutive pregnancy losses in the first trimester, most reproductive specialists and patients will want to conduct an investigation after two consecutive losses. Since there is no absolute consensus on what constitutes a comprehensive evaluation for recurrent pregnancy loss, most specialists follow some basic guidelines and select a group of tests designed to identify potential causes of repeated miscarriage. The known causes of repeat pregnancy loss generally fall into one of the following categories:
Parental chromosomal disorders
Structural abnormalities of the reproductive tract
Diminished ovarian reserve (poor egg quality)
Chromosome analysis for both parents is a standard part of the evaluation. Although an individual may have no outward signs of a chromosomal abnormality, one may be identified. Certain chromosomal abnormalities are associated with higher miscarriage rates and while we may be unable to prevent these losses, identification of one of these chromosomal abnormalities usually leads to genetic counseling and a greater understanding of their odds of a successful pregnancy.
Hormonal abnormalities include thyroid disorders, progesterone deficiency, and excessive production prolactin. While thyroid and prolactin abnormalities may be detected by simple hormonal blood tests, detection of progesterone abnormalities is more complicated since this hormone level varies on a daily basis throughout the second half of the menstrual cycle. In addition, hormone production during the second half of the menstrual cycle (luteal phase) is subject to month-to-month variation. For these reasons many practitioners recommend routine progesterone hormonal support of the luteal phase for patients with recurrent pregnancy loss in addition to treatment of any other abnormalities identified in the course of the testing.
Blood clotting disorders (thrombophilias) may be caused by excessive production of certain clotting factors. Although there are many clotting factors that could potentially be contributory to repeat pregnancy loss, it has evolved that physicians usually test for the five or six most common ones. When identified, these conditions usually are treated with agents (anticoagulants) that reduce the blood’s capacity to clot.
Structural abnormalities involving the uterine cavity may also cause recurrent pregnancy losses. Testing for these abnormalities is done by putting fluid into the uterine cavity (sonohysterogram) which separates the walls of the uterus and allows visualization of the interior of this space. Abnormalities may often be addressed through minimally invasive surgical procedures achieving excellent results.
Certain bacteria may be present without a patient being aware of their presence, and may be associated with higher miscarriage rates. These bacteria quietly reside in the reproductive tract and may reduce the chances of successful embryo implantation. A simple course of a broad-spectrum antibiotic will usually eradicate these organisms and improve prospects for successful pregnancy.
As men age they produce a greater number of genetically abnormal sperm, thereby increasing the prospects for miscarriage. Unfortunately there is currently no practical method to separate genetically abnormal sperm from normal sperm. Similarly, as women age the eggs that are released in given menstrual cycle are more prone to be genetically abnormal. We are currently unable to genetically test eggs while retaining their structural integrity. However, we can obtain general information about the quality of a woman’s eggs with respect to her age through the measurement of follicle stimulating hormone, estradiol, and anti-mullerian hormone.
Repeat pregnancy loss causes a great deal of emotional pain for couples. The feelings of loss and the grieving process are heavy burdens for couples dealing with repeated miscarriages. They sometimes blame themselves and often harbor feelings of inadequacy fearing that they will never fulfill their goal of having a family. It is important that couples suffering with repeated pregnancy loss realize that in most situations the prospects for carrying successfully are extremely good based upon available studies. Correction of any identified abnormalities coupled with encouragement, education, and emotional support are likely to result in successful live birth for the majority of couples with recurrent pregnancy loss.
