Causes of Recurrent Pregnancy Loss
Miscarriage can occur in up to 12-15% of all clinically recognized pregnancies, however the risks increases with the number of previous pregnancy losses and is modified by prior obstetric history. For example, a woman without a history of a prior live born child, but who herself has suffered 2 or more miscarriages, has a 40-45% chance for a third miscarriage. On the contrary, a woman with a history of a prior live born child followed by 2-4 miscarriages has a ~25% chance for a subsequent loss.
There are a variety of factors that may play a role in recurrent pregnancy loss, which may include but are not limited to the following:
Advanced Maternal Age
One of the most significant contributing factors for miscarriage is advanced maternal age. As women age, both reproductive potential and oocyte quality decline. The aging egg is prone to chromosomal abnormalities, which can ultimately lead to the development of a genetically abnormal embryo. Although one cannot counteract the natural reproductive aging process, your physician may be able to screen for ovarian reserve and offer genetic testing of embryos, following in vitro fertilization.
Aside from the aging egg, parental chromosomal abnormalities, such as translocations, can also increase the risk for miscarriage. A chromosomal translocation, which can be seen in 4-8% of couples with recurrent pregnancy loss, is the re-arrangement or exchange of genetic material between 2 separate chromosomes. Carriers of translocations are normal, but their eggs and sperm often carry an abnormal amount of genetic material, such that any resultant embryo is also genetically abnormal. Your specialist will recommend that both you and your partner undergo a Karyotype, which is a blood test designed to look at the chromosomes and to identify the presence of chromosomal rearrangements.
Abnormalities in uterine cavity shape can also increase the risk for miscarriage. Examples of conditions which can alter uterine anatomy include a uterine septum (a developmental abnormality of the uterus), uterine fibroids (benign tumors of the muscular layer of the uterus), and intrauterine adhesions (which may be caused by prior uterine surgery or infection). The best methods to evaluate the uterus include hysterosalpingogram (HSG), Sonohysterogram (SHG ), and hysteroscopy. Other imaging techniques, such as MRI may be used to further define pelvic anatomy or for surgical planning.
Chronic medical diseases, which have been left untreated or uncontrolled, can also lead to an increased risk for miscarriage. Examples of chronic conditions include Diabetes Mellitus, Thyroid dysfunction, and abnormalities in milk hormone (Prolactin). Your will undergo several blood tests to screen for these disorders.
Some autoimmune disorders have been linked to early pregnancy loss, including Systemic Lupus Erythematosus (SLE), autoimmune thyroid disease, and Antiphospholipid antibody syndrome (APAS). Systemic Lupus Erythematosus is an autoimmune disease which can affect the skin, heart, lungs, kidneys, joints, and even brain. Because of its effects on many different organ systems, a variety of signs and symptoms may occur. APAS is an autoimmune disorderAPAS can be seen with any woman who has had a prior blood clot, one or more losses after 10 weeks of gestation, three or more unexplained consecutive early losses, or one or more premature births (< 34 weeks gestation) due to preeclampsia or placental insufficiency. You will undergo several blood tests to screen for these disorders if your clinical history suggests them to be a potential cause.
It is important to maintain a healthy lifestyle during your journey towards building a family. Smoking, recreational drug use (cocaine), excessive alcohol intake, and obesity have all been linked to miscarriage.
Unfortunately, in over half of all cases of recurrent pregnancy loss, no reason can be identified. However, in the majority of cases, the cause for loss is a genetically abnormal embryo.
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