Recurrent pregnancy loss is classically defined as three or more consecutive miscarriages. However, the American Society of Reproductive Medicine has recently redefined it as two or more consecutive pregnancy losses. Although having a miscarriage is quite common, occurring in 15-20% of all pregnancies, recurrent pregnancy loss is uncommon and found in 2% of women.
The most common cause of recurrent pregnancy loss is genetic and usually results from chance. This occurs during fertilization when an embryo receives an abnormal number of chromosomes. It is the cause of over 50% of all miscarriages and is more common in women of increased reproductive age. Genetic problems can also result from a parent due to an irregularity in their genes, but this is much less common.
Other causes of recurrent pregnancy loss include structural abnormalities of the uterine cavity such as uterine fibroids or polyps, which are growths of the uterus, uterine adhesions from prior surgeries, and uterine anomalies such as a uterine septum, which is a wall of tissue that divides the uterus. Maternal conditions such as uncontrolled diabetes, thyroid disease, and PCOS can be a factor, as can blood clotting conditions such as antiphospholipid antibody syndrome and lupus anticoagulant.
The evaluation includes a detailed history and a pelvic exam, and lab work, including screening for diabetes, thyroid disease, and blood clotting disorders. Genetic testing with a karyotype can be performed on parents. Testing can also be performed on pregnancy-loss tissue during surgical treatment for miscarriage. Lastly, imaging can be done to evaluate for uterine anomalies or growths.
Treatment may be possible if a cause is found. In vitro fertilization can help with genetic causes. Uterine abnormalities can be treated surgically. Medical conditions such as diabetes and thyroid disorder need to be well controlled. Blood clotting disorders can be treated with blood thinners such as heparin or Lovenox or with aspirin.
Unfortunately, a cause is not identified in up to 50% of patients with recurrent pregnancy loss. This can be the most frustrating part for couples. The good news is most couples will have a successful next pregnancy even if a cause is not found.
Pregnancy loss is devastating. It is important for couples to feel supported as they grieve and try to find understanding. At Northside/Northpoint OB-GYN we hope couples feel their needs and concerns are heard and are experienced in helping couples navigate through the evaluation for recurrent loss. We also encourage couples to be optimistic as they are likely to have a healthy pregnancy in the future.