Miscarriage: Causes, symptoms, diagnosis, complications, treatments & prevention

A miscarriage is defined as loss of the products of conception before viability

  • About 15% of pregnancies are lost in the first three months.
  • More than half the miscarriages in the first 13 weeks of pregnancy are caused by chromosomal problems in the foetus
  • Miscarriages after the third month are generally due to illness or other problems with the mother

What is a miscarriage?

A miscarriage, also known as a spontaneous abortion, is defined as loss of the products of conception before viability. The products of conception are the foetus, placenta and amniotic fluid. Viability refers to the baby being able to survive after delivery. This point is at approximately 26 weeks of gestation. Normally pregnancy lasts for 40 weeks.

There are different types of miscarriage:

Threatened miscarriage

This refers to bleeding in early pregnancy associated with little or no pain. At this stage the mouth of the womb or cervix is still closed. It is important to note that most of these women will not abort.

Inevitable miscarriage

In this case the threatened miscarriage has progressed. The woman now experiences cramping pain in the back and lower abdomen. Clots are often passed as the mouth of the womb is open and the contents will be lost. Attempts to save the pregnancy at this stage are usually futile.

Recurrent miscarriage

This distressing problem affects a very small number of couples. Medical investigations are usually started after a third consecutive loss, but some doctors will investigate earlier. This is because the chances of another failed pregnancy increase significantly after two losses.

Missed miscarriage

When the foetus has died inside the womb but not been expelled, a missed miscarriage has occurred. In this case the womb will fail to enlarge and the signs of life such as the foetal heartbeat will disappear.

Septic miscarriage

Should the contents of the uterus become infected before, during or after an abortion, a septic miscarriage has occurred. This is common during unsafe abortions.

What causes miscarriage?

  • More than half of all miscarriages during the first 13 weeks of pregnancy are caused by problems in the foetus’ chromosomes. Chromosomes are tiny structures inside body cells that carry the genetic material. Each chromosome contains genes that determine a person’s appearance, sex, and blood type. Problems in the number or structure of the chromosomes or the genes can lead to miscarriage. Frequently this is nature’s way of ending a pregnancy in which the foetus was not developing normally.
  • Most chromosomal problems occur by chance and are not likely to recur in later pregnancies. In a small number of cases, however, chromosomal problems can cause recurrent miscarriages. In such cases, a karyotype to examine the chromosomal structure should be performed on the parents.
  • Certain abnormalities of the womb (uterus), which are linked to miscarriage, can be treated surgically. A special X-ray (hysterosalpingogram) or direct visualisation through a lens (hysteroscope) can detect abnormalities of the uterine cavity, and an endometrial biopsy may provide information about the uterine lining, where implantation occurs.
  • In some cases, illnesses of the mother will lead to miscarriage. Systemic lupus erythematosus, congenital heart disease, severe kidney disease, high blood pressure, uncontrolled diabetes, thyroid disease or an intrauterine infection can all interfere with the pregnancy. When these illnesses are treated, the chances for a successful pregnancy improve. Such illnesses thus require close monitoring during pregnancy.
  • Disorders of the immune system can also lead to miscarriage. The immune system defends the body against damage by recognising and attacking foreign substances. The mother’s immune system will not normally attack her foetus. Sometimes, however, this protection may be lost. Problems in the immune system can be diagnosed by blood tests.
  • Hormone imbalance may also lead to repeated miscarriage. The hormone progesterone prepares the lining of the uterus for the fertilised egg during the second half of the menstrual cycle. When an egg is fertilised, this hormone continues to prepare the uterine lining for the embryo. Enough progesterone must be produced to maintain the pregnancy, otherwise miscarriage will occur. If tests indicate that a woman’s body is not producing enough progesterone, supplements can be prescribed to correct the problem.
  • In some cases environmental and lifestyle factors lead to greater risk of miscarriage.  Exposure to high levels of radiation or toxic substances may also be factors in recurrent miscarriages.

Who suffers miscarriage and who is at risk

Spontaneous miscarriage is common with about 15% of pregnancies being lost in the first three months.

Miscarriages during the first three months tend to be due to problems with the foetus. Miscarriages occurring in the second three-month period of pregnancy tend to be related to problems with the mother.

What are the symptoms and signs of miscarriage

The main symptoms are pain in the lower abdomen and bleeding from the vagina. In an inevitable abortion, the cramping pain and bleeding may be severe.

During the physical examination the doctor will determine whether the mouth of the womb (cervix) is open. If it is, then the patient is probably experiencing an inevitable abortion. If the mouth of the womb is still closed, then a threatened miscarriage is the likely diagnosis.

How is a miscarriage diagnosed

The clinical history of pain and bleeding, and a physical examination are usually sufficient to make the diagnosis.

An ultrasound may be used to examine the contents of the womb, checking for an empty sac or signs of life in a foetus. It can also be used to see if all the products of conception have been passed.

Can a miscarriage be prevented

Unfortunately, once a miscarriage has become inevitable, attempts to save it are usually futile. Research has shown, however, that taking vitamins before and during pregnancy may lower the risk of miscarriage.

How is a miscarriage treated

This depends on the type of miscarriage. Although bed rest is usually prescribed for a threatened miscarriage, this has not been proven to be effective. The patient is encouraged not to work and to stay off her feet at home. Women are often told to avoid intercourse for a while. Although there is not much evidence that this is harmful, many people suffer guilt feelings if a miscarriage occurs after intercourse.

In any case where non-viable products of conception remain in the womb, they must be removed to prevent further bleeding and infection. This used to be known as D&C (dilation and curettage) but currently, the common practice is to empty the womb by manual vacuum aspiration when necessary. If the womb is already empty, careful monitoring may be all that is required.

Septic abortion must be treated with intravenous antibiotics and early emptying of the womb. This condition can be life-threatening.

Since many women suffer psychological problems as a result of miscarriage, counselling and support are important aspects of treatment and must not be overlooked.

What does not cause miscarriage

It must be emphasized that exercise, working, and sexual intercourse do not increase the risk of pregnancy loss in routine (uncomplicated) pregnancies. However, in the unusual circumstance where a woman is felt by her physician to be at higher risk of spontaneous abortion, she may be advised to stop working and refrain from having sexual intercourse. Women with past history of premature delivery and other specific obstetrical conditions might fall under this category.

Are there lifestyle factors associated with miscarriage

Smoking more than 10 cigarettes per day is associated with an increased risk of pregnancy loss, and some studies have even shown that the risk of miscarriage increases with paternal smoking. Other factors, such as alcohol use, fever, use of no steroidal anti-inflammatory drugs around the time of embryo implantation, and caffeine use have all been suggested to increase the risk of miscarriage, although more studies are needed to fully clarify any potential risks associated with these factors.

Of course, alcohol is a known teratogen (a chemical that can damage the developing foetus), so pregnant women are advised to abstain from drinking alcoholic beverages.

What happens during miscarriage

The symptoms you experience will depend on the cause of the miscarriage and how advanced the pregnancy is/was so may take hours, days or even weeks to complete. Usually the foetus, placenta and blood from the uterus leave the body through the vagina. You may discover during a routine scan that there is no heartbeat, or even an empty foetal sac.

Usually, by the time bleeding begins your baby has already died, unless it is around the 6 weeks period when only a small amount of blood is lost and then there is an 80% your baby will be fine.

99% of foetal deaths occur in the first 12 to 14 weeks of pregnancy (1st trimester), although the actual miscarriage may not happen for some weeks after the baby dies. Medically this is called a ‘missed abortion’. (The baby is an “embryo” to the 8th week and a “foetus” after that.)

What treatment can a woman expect when she has had a miscarriage?

The central goal of the doctor in this situation will be to try to figure out whether the woman has passed all of the tissue from the foetus and placenta. If she has passed all the tissue, she may only require observation by medical personnel. On the other hand, a woman who has not passed all of the tissue (incomplete abortion) will usually need suction dilation and curettage (D&C) of the uterus to remove any retained products of the pregnancy.

Can something be done to prevent future miscarriages?

The treatment of recurrent miscarriage depends on what is believed to be the underlying cause. This often is not as simple as it sounds. Careful evaluation may turn up several potential factors which alone or together may be responsible for the pregnancy losses.

If a chromosomal problem is found in one or both persons, then counselling as to future risks is the only option for the couple, since there is currently no method to correct genetic problems.

If a structural problem is encountered with the uterus, surgical correction could be contemplated. It should be emphasized that just because a structural abnormality is found, it does not necessarily mean that it caused the miscarriage.

Removal of a fibroid or uterine septum does not guarantee a future successful pregnancy, since the fibroid or uterine septum may not have been the cause of miscarriage in the first place.