Early pregnancy loss is unfortunately a common occurrence, affecting 1 in 3 or 1 in 4 women. A very small percentage of women (5%) experience recurrent pregnancy loss (RPL), a condition defined as 2 or more miscarriages. Less than 1% of women experience 3 or more miscarriages. To answer the question of why miscarriages happen, taking a closer look at the common causes of miscarriage can help shed some light.
There are normally 46 chromosomes that contain the genes for normal develop-ment. When an embryo has an extra chromosome or one is missing, these genetic abnormalities frequently interfere with the healthy development of the baby, resulting in a miscarriage or serious health disorders. Chromosomal abnormalities occur for unknown reasons in up to 60% of first-trimester miscarriages. As a woman ages, her risk for miscarriage due to genetic abnormalities increases — from 10% to 15% in women younger than 35 years old to more than 50% in women over 40 years old.
Uterine abnormalities, such as a septum, fibroid, polyp, or other problems in or near the uterine cavity as well as untreated medical conditions such as thyroid disease or diabetes can increase the risk of miscarriage. Abnormalities of the immune system and blood-clotting system (thrombophilia) can also cause repeated miscarriages. Smoking, the use of recreational drugs and excessive alcohol intake increase the chances for miscarriage as well.
Women who experience multiple miscarriages are given a thorough medical evaluation and undergo several tests. Blood tests can often reveal if a woman has medical, immune or blood-clotting disorders. A specialized blood test called karyotyping, in which the chromosomes of each partner are studied, helps detect a genetic cause of pregnancy loss. Imaging tests are also used to help spot anatomic abnormalities of the uterus.
For approximately 20-30% of women, there simply is no explanation for their mis-carriage.
Fortunately, even after several pregnancy losses, women have as much as an80% chance for carrying a full-term pregnancy.
If you’ve suffered several miscarriages and are seeking the expertise and compas-sion of a fertility specialist who can help answer your questions, contact one of our physicians.