The loss of any pregnancy can result in significant grief and sorrow for couples. Questions relating to why and how did miscarriage occur naturally arise from this distressing event, and many couples wonder when they should seek consultation for treatment of pregnancy loss. Miscarriage is not an uncommon occurrence.

Approximately 15 to 20 percent of clinically detectable pregnancies are lost to miscarriage. A clinically detectable pregnancy is defined as a gestational sac detectable by ultrasound. Most authorities agree that it is usually best to reserve extensive evaluation until at least two or three consecutive miscarriages occur. Under these circumstances, a cause for recurrent miscarriage will be identified in about half of the couples and treatment can often resolve the problem. This section will define miscarriage, identify the common causes of miscarriage, and outline when the pursuit of diagnosis and treatment are recommended.

A miscarriage is defined as the loss of a pregnancy before 20 weeks gestation. Most miscarriages, also referred to as spontaneous abortions or pregnancy losses. occur within the first trimester, defined as the first 12 weeks of pregnancy. Studies have shown that if a viable, fetus (one whose heart activity is seen by ultrasound} is detected in the first 12 weeks of gestation, there is only about a five to 10 percent chance that the pregnancy will result in miscarriage. If vaginal bleeding occurs after a viable fetus has been documented, however, the chance of miscarriage is increased to about 20 percent. The risk of a pregnancy terminating in miscarriage becomes greater with the age of the mother or the father.

The risk of miscarriage increases for women 35 years or older. The chances of having a repeated miscarriage vary widely. Women who have had at least one full term normal delivery have an improved chance of a subsequent healthy pregnancy despite experiencing a miscarriage. A woman with a history of three consecutive miscarriages, but no live births, has a 50 percent chance of having a miscarriage in the next pregnancy. However, if she has had at least one live birth, followed by three miscarriages, the chance that her next pregnancy will end in a miscarriage is only about 30 percent.


The major cause of an early miscarriage is probably a genetic (inherited) factor. An estimated 50 to 60 percent of all first trimester miscarriages of a single fetus (not twins or more) show evidence of genetic defects. The most common genetic defect resulting in miscarriage is an abnormal number or structure of chromosomes. Chromosomes are located in the nucleus (center) of cells and contain the genes, which are the basic units of inherited characteristics. If it is determined that a pregnancy loss is due to a chromosomally abnormal fetus, there is a greater chance that a subsequent pregnancy will also be abnormal. However, if the chromosomal examination of the fetus is normal, there is a reduced chance that a subsequent pregnancy will be chromosomally abnormal.

In order to determine whether there is a genetic cause for repeated pregnancy loss. physicians may order a karyotype on the fetal tissue (which is generally obtained during a D&C) and on blood from both parents. If the karyotype is abnormal, there is usually no therapy available, but the information may help to explain recurrent pregnancy loss for these couples. In about five percent of cases, a chromosomal abnormality is found in one of the parents. If both parents have a normal karyotype, it is likely that the miscarriage was a chance event and the couple should feel comfortable continuing to try to have a baby. In cases of abnormal karyotypes, genetic counseling to discuss the degree of risk may be recommended.

Chromosomal analysis may also be recommended to couples who have had a child with multiple congenital defects (birth defects), or who have a history of one or more pregnancies ending in fetal or newborn death. Chromosomal problems found in these couples often involve structural changes in the chromosomes.

In cases where genetic abnormalities will lead to continued pregnancy losses, the couple should discuss treatment options with their physician. Options may include continuing efforts to have a baby using their own eggs and sperm: using donor eggs or a surrogate mother (if the woman has the genetic problem): or using donor sperm (if the man has the genetic problem).

Uterine Abnormalities

Approximately 10 to 15 percent of women with a history of recurrent miscarriage have an abnormally shaped uterus. One example of an abnormally shaped uterus is a septate uterus, which involves a central ridge or septum of tissue protruding into the inner cavity of the uterus (Figure I). This congenital abnormality occurs in about three percent of women, and only half of these women have reproductive difficulty. Theoretically, a miscarriage occurs in a septate uterus because the blood supply to the septum may not adequately support normal fetal growth.
Normal Uterus

Other birth defects of uterine shape (also known as congenital uterine malformations) can likewise result in pregnancy loss. One subset of women with uterine abnormalities are those whose mothers took diethylstilbeslrol (DES) while pregnant. Women exposed to DES who subsequently become pregnant have a significantly greater incidence of miscarriage, premature labor, and infertility.

Uterine fibroids can also cause an abnormally shaped uterus. Uterine fibroids are common, noncancerous tumors in the wall of the uterus which can interfere with the implantation or growth of a fetus. Fibroids can increase in size during pregnancy and result in miscarriage (Figure 2).

Figure 1 : An abnormally shaped uterus may cause miscarriage.

A special x-ray called a hysterosalpingogram (HSG) can identify abnormalities within the cervix and uterus. It is also used to determine if the fallopian tubes are open. This procedure involves injecting a special solution through the cervix. As the solution travels through the uterus and the fallopian tubes, x-rays reveal the inner shape of these organs. An HSG is performed after menstrual bleeding stops and before ovulation occurs. Moderate cramping usually follows an HSG and can be eased with medication. Antibiotics are sometimes prescribed for several days to reduce the risk of infection.

Another procedure used to examine the uterine cavity (inside of the uterus) is called hysteroscopy. A narrow, lighted telescope-like instrument called a hysteroscope is inserted through the cervix into the uterus so that the physician can view the uterine cavity. This procedure is usually performed on an outpatient basis with either general or local anesthesia or during a laparoscopy.

A new technique. sonography involves injecting fluid into the uterus and tubes and observing the ultrasound-produced image of these structures. This procedure avoids the use of x-rays.

Figure 2 : Fibroids in the uterus may cause miscarriage

Cervical Abnormalities

In some cases the cervix, which is the narrow. lower end of the uterus, is too weak to support a pregnancy without surgical correction. In these patients, the cervix begins to open prematurely. Up to 16 percent of midtrimester (12 to 20 weeks) pregnancy losses are caused by this condition, known as cervical incompetence. A special ultrasound or an HSG is sometimes used to diagnose cervical incompetence. Once an incompetent cervix has been discovered and surgery is performed, a subsequent pregnancy can usually be carried to term. The surgical procedure for correcting cervical incompetence is referred to as cerclage. also know as a “cervical stitch.

Hormonal Abnormalities

Disorders of the thyroid gland. such as overactivity (hyperthyroidism) or underactivity (hypothyroidism). have been linked to miscarriage. Thyroid antibodies have also been associated with a two-fold increase in miscarriage. Once a diagnosis of hypothyroidism. hyperthyroidism. or thyroid antibodies is made with a blood test. These disorders can be effectively treated with proper medication.

The luteal phase or second half of the menstrual cycle, is a critical time when the endometrium (lining of the uterus) responds to the hormone progesterone. which is produced by the ovaries after ovulation. Under the influence of progesterone, the endometrium thickens and becomes a healthy environment for a growing embryo.

However, if progesterone production is low. infertility or miscarriage can result. This occurs because the endometrium fails to become a nourishing environment. preventing the embryo from implanting securely. This problem is often called a luteal phase defect, which can sometimes result from abnormal hormone levels or poor ovulation.

An endometrial biopsy is generally used to detect problems in the luteal phase. This office test is done just before menstruation begins. A small amount of endometrial tissue is taken from inside the uterine cavity and examined under a microscope. Results indicate whether or not the endometrium is responding normally to progesterone production.

If prolactin. a pituitary hormone that stimulates milk production, is elevated, disturbances in ovulation and the luteal phase can occur. One indication of elevated prolactin levels is the presence of galactorrhea, a milky discharge from the nipple of a woman who is not nursing. A blood test is used to measure the prolactin level. Medication is usually effective in lowering elevated levels.

A luteal phase defect can be treated with clomiphene citrate. Human menopausal Gonodotropins (hMG) and/or natural progesterone. Clomiphene citrate is a tablet and hMG is an injection given to enhance the production of ovarian hormones, thereby improving ovulation and increasing the development of the uterine lining. Natural progesterone, administered orally, as a vaginal suppository or an injection, is given during the luteal phase. Since progesterone is natural (in that it is identical in structure to that made by the ovaries) rather than synthetic (a chemically modified form of progesterone), its use has not been associated with an increased risk of birth defects.


Infections may cause recurrent pregnancy loss but studies have failed to indicate a greater incidence of infection in women with a history of recurrent miscarriages when compared to normal fertile women. For example, chlamydia has been linked to miscarriages but is more clearly associated with tubal infection and infertility. Mycoplasma has also been implicated as a cause of recurrent pregnancy loss but the evidence is not strong.

When evaluating a couple with a history of repeated early pregnancy loss. Many physicians will take cultures to check for infectious organisms. If an infection is identified, antibiotics are usually prescribed for both partners and a re-culture is done. However, there is no definite proof that antibiotic treatment will increase the chances of a normal pregnancy.

The Immune System

The human immune system plays an important role in maintaining general health and responding to infection, injury, or introduction of foreign material. At this time the immunologic interaction between mother and fetus is not clearly understood, but its role in repeated pregnancy loss is now under intense investigation and falls into two general categories.

The first category involves the production of certain immunoglobulins or antibodies which the pregnant woman’s body creates and directs against circulating substances that affect blood clotting. Examples of these antibodies are the lupus anticoagulant, the anticardiolipids, and the antiphospholipids. These antibodies can affect fetal development, often resulting in miscarriage.

The second category involves an alteration in the immunologic response of the mother against the pregnancy. Current theory suggests that during a normal pregnancy, the fetus, which carries the father’s foreign genes, survives in the mother’s uterus because of a special protective response from the mother’s immune system. For certain couples, this protective response does not occur, and the maternal immune system is activated to reject the father’s foreign material in the fetus, resulting in miscarriage.

Unfortunately, at present there are few tests to determine whether an immune cause is the reason for a miscarriage. Most involve blood tests on the father and mother, but these tests do not always provide clear-cut answers. Treatment for the immune causes of recurrent miscarriage is also controversial. If antiphospholipid antibodies are identified, for example, the physician may prescribe small amounts of heparin or aspirin, or a steroid preparation called prednisone. Other therapies including various types of immunization to prevent the maternal immune system from rejecting the fetus.

Maternal Illness

Certain maternal illnesses have been associated with a higher rate of pregnancy loss. These medical conditions include autoimmune diseases, congenital heart disease, severe kidney disease, and uncontrolled diabetes. Treatment of some of these illnesses can improve chances for successful pregnancy, especially prior to conception and during the first 12 weeks of pregnancy. Special care and monitoring during the entire pregnancy is recommended.


Smoking, drinking, and illegal drug use can increase the risk of miscarriage. However, exercise, working, intercourse, and exposure to video display terminals and computers do not increase the risk of miscarriage, nor does the use of hair spray. hair coloring, or permanents. Although most medicines do not have an effect on pregnancy. there are some which may lead to miscarriage and birth defects. Women should always consult their physician before taking any medicine during pregnancy. and also need to alert doctors and dentists before receiving x-rays or prescriptions for medication. If couples are concerned that their home or work environment may contain hazardous agents, they should consult their physician about this issue.


Experiencing a miscarriage often creates feelings of shock, disbelief, guilt, anger. sadness, loneliness, and depression. After a miscarriage, it’s normal for couples to experience a period of grief and to repeatedly ask themselves why this has happened. With repeated miscarriages, these feelings can become more intense. These feelings are normal, and it is important to understand that women and men may feel and cope differently with this loss. Grieving is a very personal experience. It is helpful if both partners realize this and not expect their reactions to be the same.

To aid in healing, a woman should eat a balanced diet that includes protein. vegetables, fruit, and whole grains. Engaging in physical activity every day is very therapeutic, even if the activity is just a short walk around the block. Getting adequate rest is also important and encourages the healing process. Some couples need to symbolically acknowledge their loss by having a memorial service, giving a donation to a favorite charity, or planting a special tree.

Although it may be difficult, couples should talk about the loss of their pregnancy and their” feelings with family and friends. Reading literature about miscarriage often provides comfort and support. Recording thoughts in a diary or journal can also be helpful. Some couples write letters as a means of saying goodbye and dealing with the loss. It is helpful to seek support from others who have had similar experiences. Talk with friends, join support groups, or see a professional counselor.


Knowledge of miscarriage is still limited. No obvious cause is detected in up to 50 percent of couples with repeated pregnancy losses. Some women who have experienced recurrent miscarriage may feel doubtful that they will ever have a child. but the encouraging news is that the success rate with treatment is high especially with certain uterine and hormonal causes. In cases where no cause is discovered and no treatment prescribed, the chance of achieving a healthy pregnancy despite having had several miscarriages is still generally better than 50 percent.