Recurrent miscarriage at a glance
- Recurrent miscarriage is when a woman has two or more clinical pregnancy losses (miscarriages).
- After three miscarriages, the American College of Obstetricians and Gynecologists (ACOG) recommends a physical exam and further testing, but Women & Infants’ Fertility Center initiates an evaluation after two miscarriages.
- Nearly two-thirds of women who have recurrent miscarriages will eventually carry a full-term, healthy pregnancy, often without treatment.
What is recurrent miscarriage?
Recurrent miscarriage, also called recurrent pregnancy loss or habitual abortion, occurs when a woman has two or more consecutive clinical pregnancy losses. Doctors define a clinical pregnancy as one having clinical evidence of the pregnancy, such as visual or laboratory indications of the gestational sac (cavity of fluid surrounding an embryo), placenta or the fetal pole (thickening on the margin of the yolk sac of a fetus) on an early ultrasound.
Clinical pregnancies differ from chemical pregnancies, during which a miscarriage occurs before there is any evidence of the pregnancy aside from a positive pregnancy or blood test. Of all clinical pregnancies, 15 to 20 percent end in miscarriages.
The likelihood of recurrent miscarriage is small. According to ACOG, about 5 percent of women have two or more consecutive miscarriages and 1 percent will have three or more. The risk of recurrent miscarriage is higher in women who are over the age of 35 or who have had previous miscarriages.
The incidence of miscarriage is likely underreported, as many women have miscarriages before they even knew they were pregnant and do not experience any signs or symptoms of the miscarriage. In most cases, a healthcare provider can detect and diagnose a miscarriage by using an ultrasound (a diagnostic imaging technique that uses sound waves).
The majority of miscarriages occur as a result of genetic abnormalities in the embryo or fetus, such as an extra chromosome or missing chromosomes. These are typically random mutations that are not likely to recur. In recurrent miscarriage however, the situation is different and the doctor will look for a specific type of mutation called a balanced translocation. While associated with recurrent miscarriage, it is still a very uncommon occurrence.
Some women who have a miscarriage or recurrent miscarriages experience vaginal bleeding, loss of tenderness or fullness in the breasts, and the loss of fetal movement or sound. Women should report such signs to their doctor or midwife and keep track of the amount of bleeding that occurs.
If a patient passes tissue during a miscarriage, she should save it. A doctor can later use it to help determine the cause of the miscarriage.
A miscarriage can cause deep-rooted feelings of loss and sorrow. Some doctors suggest that patients join a support group to talk about their experience and grief associated with the loss of the pregnancy and the baby. Women & Infants Hospital offers two pregnancy loss support groups: Miscarriage, Infant Death and Stillbirth (MIS) Group and Pregnancy After Loss Support (PALS) Group. For information, call (401) 274-1122, ext. 44049 or click here.
What causes recurrent miscarriage?
According to ACOG about 60 percent of all recurrent miscarriages are a result of a genetic abnormality. As a woman ages, the risk of miscarriage due to genetic abnormalities increases from 15 to20 percent if she is under age 35, to more than 50 percent if she is over 40 years old.
A genetic abnormality can occur when an embryo (fertilized egg) receives an abnormal number of chromosomes during fertilization. This type of genetic cause usually occurs by chance and there is no medical condition associated with it. In a small number of couples who have recurrent miscarriages, one partner may have chromosome translocation (when one piece of a chromosome breaks off and reattaches to a second chromosome).
A septate uterus, in which a wall of tissue divides the uterus into two sections, occurs very commonly and can result in recurrent miscarriage. While it is not entirely clear why this leads to recurrent miscarriage, some providers believe that poor vascularity in the septum causes the embryo to stop growing if it implants there. If the pregnancy does make it to term, the fetus may be breech. Fortunately, removing a uterine septum is typically very easy to do surgically.
An incompetent cervix is one that cannot remain closed due to weakened muscles. As the developing fetus reaches a certain weight, the weakened cervix cannot support the fetus and sometimes results in miscarriage.
Various types of medical conditions can increase the risk of recurrent miscarriage including:
- Antiphospholipid syndrome (APS) – An autoimmune disorder that occurs when a person’s immune system mistakenly makes antibodies to certain substances that are necessary for blood clotting.
- Thyroid/hormonal issues – An overactive or underactive thyroid (endocrine gland at the base of the neck) can result in hormonal imbalances. Hormonal imbalances can cause a miscarriage if the uterine lining doesn’t develop normally for implantation and nourishment of a fertilized egg. Elevated prolactin (reproductive hormone produced in the pituitary gland) levels can alter proper development of the uterine lining.
- Fibroids and polyps – Noncancerous growths that can grow into and invade the uterus.
- Asherman’s syndrome – A condition in which scar tissue forms inside the uterus and may result in miscarriage.
Diagnosing recurrent miscarriage
To determine the cause of recurrent miscarriages, a fertility specialist or an ob/gyn will review a patient’s medical history and past pregnancies. A doctor will usually recommend a complete physical exam, including a pelvic exam.
If the recurrent miscarriages are suspected to be the result of a genetic error, the doctor may perform a karyotype, a test that identifies and evaluates the size, shape and number of chromosomes in a sample of body cells.
If a doctor suspects the cause of recurrent miscarriage is due to a uterine problem, he or she will likely perform imaging tests, such as an MRI or a sonogram/ultrasound. A hysterosalpingogram (HSG) (an X-ray of the fallopian tubes and uterine cavity) or an ultrasound can show if a woman has a problem with the shape of her uterus. A physician may conduct blood tests to detect problems with the immune system, such as APS.
Approximately 50 percent of patients who are evaluated for recurrent miscarriage have a clear diagnosis. The remaining patients do not have a defined cause of their recurrent miscarriage diagnosis.
Within the group of patients who do not know the cause of their diagnosis, the chance of a successful future outcome can be as high as 70 percent, depending on the maternal age of the patient.
Treatment for recurrent miscarriage
Treatments for recurrent miscarriage can involve lifestyle changes, medications, surgery or genetic tests to increase the chance of a successful pregnancy. With certain conditions surrounding recurrent miscarriage, medical or surgical treatments can lower a woman’s risk for future miscarriage.
Even after having three miscarriages, a woman has a 60 to 80 percent chance of conceiving and carrying a full-term pregnancy. Often women decide to continue trying to get pregnant naturally, but in certain situations a doctor may suggest treatments to help reduce the risk of another miscarriage.
Surgery can fix problems with a septate uterus and can eliminate some fibroids or scar tissue irregularities. Surgical correction is often the treatment of choice for anatomical issues since it improves live birth rates.
If the patient has an autoimmune problem, such as APS, a doctor may prescribe blood thinning medications such as a low-dose aspirin or heparin. Although a patient can take blood thinning medications during pregnancy to lower the risk of a miscarriage, she should talk with a doctor before using them, due to the increased chance of serious bleeding problems.
Treating medical problems such as abnormal blood sugar levels, thyroid issues or hormonal imbalances can improve the chances of having a healthy, full-term pregnancy. Medications that activate the dopamine receptors in the brain or progesterone supplements can aid this process.
If a doctor finds a chromosomal problem such as translocation, he or she may recommend genetic counseling. While many couples with translocations conceive a healthy pregnancy naturally, a doctor might suggest fertility treatments such as in vitro fertilization (IVF), a process in which a reproductive specialist combines eggs and sperm in a lab. The embryos can then be genetically tested using a technique called preimplantation genetic diagnosis (PGD), and only normal ones are transferred to the uterus. This improves pregnancy outcome.
Making good lifestyle choices, such as stopping cigarette smoking or illicit drug use, limiting alcohol and caffeine and maintaining a healthy weight, may lower the risk for recurrent miscarriage. There is no proof that stress, anxiety or mild depression cause recurrent miscarriages.