Miscarriage is one of the most difficult conditions patients have to face and is magnified in those who have recurrent miscarriage.
Miscarriage is especially painful for those patients who underwent months of fertility therapy in order to become pregnant. Recurrent miscarriage is typically defined as three or more consecutive pregnancy losses that occur prior to 24 weeks of gestation. First trimester losses are the most common and occur prior to 12 weeks of gestation.
A woman’s reproductive history influences the chances for miscarriage and includes factors such as previous miscarriage, female age, presence of a condition such as PCOS, and other factors. When a patient has had two or more miscarriages, the chances for future miscarriage is increased.
Miscarriage is more common than many people believe and occurs in 15-20% of pregnancies in women under the age of 30, 20-30% for women in their 30’s, and often greater than 50% of the time for women over the age of 40. In approximately 50% or more of these cases, miscarriage is the body’s way of screening for an abnormal fetus that cannot survive. One of the most common causes of miscarriage is an abnormal number of chromosomes in the embryo. This condition is known as aneuploidy and increases as women age.
Causes of Miscarriages
One cause of repetitive miscarriages due to genetic problems in the fetus is when the male and female have a balanced chromosomal translocation. This is found in 3-4% of cases where there were 3 or more miscarriages. Genetic testing consists of obtaining a blood test for high resolution/definition peripheral blood karyotype (chromosome analysis). If a balanced translocation is found, the affected person usually has the normal amount of DNA material but when eggs or sperm are made, there may be either too much DNA or not enough. This may increase the risk for miscarriage.
Polycystic Ovary System (PCOS)
Some medical conditions, including PCOS, increase the chances of miscarriage. Pretreatment prior to conception with insulin sensitizing agents such as Glucophage (Metformin) may decrease this risk for some patients.
Uterine abnormalities such as congenital or acquired malformations may be a cause. Congenital malformations include double uterus (uterus didelphysis), a singled sided uterus (unicornuate uterus), a heart shaped uterus (bicornuate uterus) and a septate uterus (mid-line muscle growth in the uterine cavity). Most of these abnormalities decrease the chance of pregnancy, increase the risk of miscarriage and also increase the risk of preterm labor.
Thrombophilic (blood-clotting) tendencies may impair the development or function of the placenta. Abnormal blood clotting in the placental blood vessels may result in recurrent miscarriage. This may be due to antibodies to phospholipids (antiphospholipid antibodies) which are important components of the membrane that surrounds all cells and small blood vessels. For this reason, aspirin and/or heparin may be used in some cases of recurrent miscarriage. Dr. Ware Branch, a maternal fetal medicine expert at the University of Utah, is one of the world’s experts on this particular syndrome.
Some specialists believe miscarriage can result due to an abnormal autoimmune response. When this happens, the body “mistakes” the fetus for an invading pathogen and creates antibodies to destroy it. This type of evaluation can be expensive and recommended treatments in the past have often been proven to be ineffective. Most of these conditions are identified in the workup for infertility.