A miscarriage, also called a spontaneous abortion, is the unintentional loss of a foetus before the 20th week of pregnancy. A miscarriage in the first two to four months is called an early miscarriage.

It is important to understand that miscarriage is almost always something that is outside your control - so, if you are affected, it is important not to blame yourself.

The causes of miscarriage are not well understood; and the likelihood is that if you do suffer a miscarriage, no one will be able to tell you why.

A miscarriage may be caused by problems that occur during the delicate process of early development, for example, when an egg fails to implant properly in the womb or when the embryo has structural defects that don’t allow it to develop normally.

The most common underlying reason is a chromosomal abnormality in the fertilised egg. This may means that either the egg or the sperm had the wrong number of chromosomes to start with and, as a result, the fertilised egg is unable to develop normally. In some cases this can lead to the situation where the placenta and embryo sac begin to develop but there is no baby inside. Chromosomal disorders during fertilisation are not necessarily a sign of a hereditary disorder, and as a rule, have no bearing on subsequent pregnancies.

It is only after multiple miscarriages (habitual abortion) that the causes of miscarriage are investigated more closely.

The most common signs of a threatening miscarriage include vaginal blood loss and menstruation-like abdominal cramps in early pregnancy. You should always see a doctor if you have any vaginal bleeding during pregnancy. Your doctor will examine you to see if bleeding is coming from your cervix and check your uterus (womb). They may also do a blood test to assess levels of the pregnancy hormone. However, in approximately half of these cases, there is fortunately nothing wrong.

Your doctor may refer you for a scan to help determine if your baby is alive. If that shows that the embryo is not viable, or no longer viable, then a miscarriage will often occur spontaneously within a few days of this blood loss, although it may take longer to start. In this situation, the miscarriage can either be left to occur naturally or triggered by curettage. This depends on personal preference and how long it takes for the spontaneous miscarriage to occur. In order to follow a natural course of events, it is generally advisable to wait for a spontaneous miscarriage. But in the unfortunate event that you were to find yourself in such a situation, your doctor would discuss these options with you.

During a spontaneous miscarriage, abdominal cramps will subside and blood loss will become comparable to a heavy menstruation. If cramps or blood loss continue after the miscarriage, a fever develops or if you are worried about the course of the miscarriage, then it is advisable to contact your doctor. You may need a curettage is if the miscarriage was not complete (incomplete miscarriage) in which case blood loss continues.

Obviously pregnant women who experience vaginal blood loss at the start of their pregnancy are very concerned about miscarriage. You should always see a doctor if you have any vaginal bleeding during pregnancy. However, vaginal blood loss does not always point to a miscarriage.

Early blood loss may be caused by a cervix that bleeds easily due to, perhaps, a polyp or infection. This vaginal blood loss is often noticed after intercourse or during constipation (hard stool). Occasionally, the reason may be an ectopic pregnancy; this is often coupled with quite severe abdominal pains. A less common cause of vaginal blood loss is the death of one embryo in the event of a multiple-pregnancy. Alternatively bleeding next to the embryonic sac could be the cause. If no reason can be found, then it may be that the blood loss is entirely innocent and caused by the implantation of the embryo into the lining of the womb. This is called implant bleeding.

Very early ultrasound does not always provide an indication of the viability of the pregnancy. If an embryo is not observed, or a heart beat not registered, the ultrasound will usually be repeated at least one week later. If after this it appears that the embryonic sac is empty, or there is no heartbeat, then unfortunately nothing can be done to “save” the pregnancy. Although the pregnancy will probably result in a spontaneous miscarriage, it is difficult to predict when this will happen. Your doctor will discuss with you the options available to you.

You can opt to wait for a spontaneous miscarriage, thereby giving nature a chance to run its course. It is advisable to set a deadline with your doctor as to how long you are prepared to, or can, wait for this to occur. You can also choose to trigger the miscarriage through curettage. Here you will receive a short-term anaesthetic and a gynaecologist will empty the uterine cavity through the vagina. Technically, this is a minor operation, with only a very small chance of complications arising. The choice depends on your personal preference.

Even if you decide to wait, a spontaneous miscarriage may still, however, take too long and necessitate curettage. If it appears that the miscarriage was incomplete (the blood loss continues after the miscarriage), a subsequent curettage may also be necessary.

The experience of three or more consecutive miscarriages is referred to as habitual abortion or repeated miscarriage. This occurs in 0.5 - 1% of pregnant women.

Just as with a one-off miscarriage, the reason for a repeated miscarriage is generally a chromosomal disorder arising during fertilisation; the embryo does not grow and is rejected by the body. It is not known why this occurs more frequently in some women than others. In cases of habitual abortion, the possibility of undertaking a closer investigation to identify the cause will be discussed with the couple. However a cause for repeated miscarriage is only identified in approximately 15% of couples. It is important to bear this in mind before hand, and also to be aware that, should a reason be found, it is often untreatable.

Closer examination to unearth the cause of habitual abortion mostly entails an examination for chromosome abnormalities, an ultrasound examination of the uterus (womb) and ovaries as well as blood tests. Multiple pregnancy, the advancing age of the mother and the state of health of the mother (whereby smoking /drinking habits and environmental factors play a role) can all affect the chances of a miscarriage occurring.