Approximately 15% of pregnancies between 4-20 weeks end in spontaneous abortion. Recurrent miscarriage is defined as three or more consecutive spontaneous abortions. Recurrent miscarriage in fertility patients is especially tragic because they have often undergone months of therapy to achieve pregnancy.
The most common causes of recurrent miscarriage are genetic abnormalities, uterine structural deformities, and endocrine diseases. The incidence of spontaneous abortion increases as women age, which is most likely due to chromosome abnormalities. It is also higher in women with polycystic ovarian syndrome.
The child receives half of his/her genetic material from the father and half from the mother. The most common cause of miscarriage is genetic abnormalities, usually occurring as a random event. In most cases, genetic abnormalities are not seen in the parents. In the fetus, the most common genetic cause is aneuploidy, or an abnormal number of a particular chromosome (i.e. 3 chromosomes instead of 2). In particular, chromosomes 13, 16, 18, 21, and 21 are common for aneuploidy. A fetus may also have only 1 copy instead of 2 of a particular chromosome, which can cause pregnancy loss.
In some cases, the couple may have a known genetic disease that could be transferred to their child. Preimplantation genetic diagnosis (PGD) can be used to screen for certain genetic diseases such as hemophilia, Tay- Sachs, and many others. The couple undergoes an IVF cycle and the resultant embryos are biopsied to learn if they carry the disease. This process is especially useful in couples who have “sex-linked” diseases. Embryos of the affected sex are not transferred to the mother.
Even though PGD is an extremely useful diagnostic/screening tool, it does not replace an amniocentesis during pregnancy.
Uterine abnormalities are a cause of recurrent miscarriage. Uterine malformations include the septate uterus, Asherman’s syndrome, large polyps or fibroids, and uterine scarring from infection. With today’s surgical techniques many of these conditions can be corrected by a reproductive surgeon, however, conditions such as a unicornuate uterus cannot be surgically treated. When structural damage is severe the only option for couples desiring a genetically related child is to use a surrogate mother.
Endocrine, or hormonal, disorders are also a cause of recurrent miscarriage. Polycystic ovarian disease is associated with elevated levels of luteinizing hormone and testosterone, which are linked to miscarriage. Type 1 diabetes and untreated thyroid disease are all implicated as other potential endocrine causes of recurrent miscarriage.
During a normal ovulatory cycle, the lining of the uterus (the endometrium) develops under the influence of the hormones estrogen and progesterone. The endometrium must thicken and become more vascular to accept a developing embryo. Failure of the endometrium to develop properly on a regular basis, generally termed a luteal phase defect, could lead to poor implantation and subsequent pregnancy loss.
Antiphospholipid antibody syndrome is a well characterized cause of spontaneous abortion. In this syndrome the body mistakes phospholipids (a component of the cell membrane) as an antigen (invading pathogen or allergen) and produces antibodies to destroy them. Lupus anticoagulant and/or high anticardiolipin antibodies have been associated with first, second, and third trimester spontaneous abortions. It is postulated that the antibodies cause small clots in the vessels of the placenta restricting blood flow. This syndrome also causes poor fetal growth, high blood pressure in the mother, and stillbirth.
Our reproductive specialists have years of experience managing women who suffer from recurrent miscarriage and infertility. Their combined experience is unparalleled in the region and you can be assured of a complete evaluation of your condition and the most current and effective treatments.