Recurrent Pregnancy Loss (RPL)

Recurrent pregnancy loss, also known as habitual abortion, is the miscarriage of two or more pregnancies, usually in the first trimester (earlier than 12 weeks of gestation), but sometimes in the second trimester (from 12 to 24 weeks of gestation) as well. The risk of a single miscarriage ranges from 15% to 50% or more per pregnancy, depending on the woman’s age as well as medical factors. By contrast, the risk of multiple miscarriages is much lower, generally occurring in less than 5% of women trying to conceive. The cause(s) for RPL remain unknown in about half of cases, despite extensive diagnostic testing. The identifiable causes of RPL include genetic abnormalities, anatomical problems, infectious causes, immunological problems, blood clotting disorders, hormonal abnormalities and environmental toxins.

Diagnostic testing includes the following:

Blood Chromosome Testing of Each Partner

The chromosomes are structures in the nucleus of each cell of the body. These structures contain the genes that determine the form and function of every part of the body. In some couples with RPL, one or both partners may contain abnormalities in their chromosome structure that causes a resulting embryo to carry an abnormal amount of genetic material, usually resulting in miscarriage. Furthermore, an embryo can have a chromosomal abnormality due to random chance alone, with no abnormalities in the chromosomes of either parent. In cases of RPL due to chromosomal abnormalities, one possible therapy to consider is in vitro fertilization (IVF) with a biopsy and chromosomal evaluation of each embryo, called preimplantation genetic diagnosis (PGD).

Anatomical Abnormalities

The uterus might have congenital abnormalities that make embryo implantation and/or development difficult. These abnormalities include uterine septums, bicornuate uteri and unicornuate uteri. Furthermore, some abnormalities can develop during a woman’s lifetime, including uterine scarring from infections, abortions, dilatation and curettage (D&C) procedures, and surgery of the uterus. Diagnostic tests include hysterosalpingograms (HSG), saline sonohysterograms, and hysteroscopy.

Infectious Causes

There are many conflicting studies in the medical literature regarding the role of vaginal or uterine infections as risk factors for miscarriage. Some patients and their partners receive antibiotic treatment but the benefits of such treatment remain unproven.

Immunological Causes

In some women with RPL, the cause appears to be related to circulating antibodies that attack the fatty material (phospholipids) that compose certain cells important in sustaining the pregnancy. Blood tests are performed to identify these antibodies and blood thinning medications can be used in treatment.

Blood Clotting Disorders (Thrombophilias)

Some women with RPL have been shown to have inherited disorders that cause clots in the blood vessels that sustain the developing embryo and fetus, thus interrupting embryo development and fetal growth. In these women, there is an increased risk of developing potentially life-threatening blood clots in the veins and arteries of the woman. Blood thinning medications are used in women with inherited blood clotting disorders to prevent these serious complications. Data regarding the benefits of blood thinning medications to prevent miscarriage are controversial.

Hormonal Abnormalities

Women with uncontrolled diabetes mellitus and uncorrected thyroid-gland dysfunction are at an elevated risk of miscarriage. The principal hormone that helps sustain a pregnancy is progesterone. In some women, the uterine cavity appears to be inadequately stimulated by progesterone, a potential factor in miscarriages. While in most cases, low progesterone levels are likely the consequence of a miscarriage rather than the cause, in some cases supplementation with progesterone, or other medications that increase progesterone’s effects, might be warranted.

Tests and treatments
with no proven benefit for recurrent miscarriage

The search for a solution for many couples with RPL has led to the use and development of several tests and therapies that currently have not been proven to be useful and are often very expensive. These tests and therapies include but are not limited to the following:

Bacterial and viral cultures
Maternal antibodies directed against paternal cells
Chemicals toxic to embryo development (embryotoxic factors)
Intravenous immunoglobulin (IVIG)
White blood cell (leukocyte) immunization

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