While over 50,000 Irish women give birth every year, it is estimated that a further 14,000 women miscarry spontaneously every year. This can be an immensely difficult time, both for women and their partners. About half of Irish women who miscarry will require hospital admission. Sometimes miscarriages occur very early in the pregnancy, before a woman even suspects she may be pregnant. In this situation a menstrual period is later and heavier than usual.

Most women realise that they are miscarrying when they start to bleed, and have pain. The bleeding can vary from bright red to dark brown. This may be accompanied by cramping pains in the lower abdomen and the lower back. Sometimes women will bleed in early pregnancy and still proceed with the pregnancy without any further problems. However any bleeding in early pregnancy needs to be assessed by the patient's doctor. Approximately 15% of all pregnancies end in miscarriage.

Types of miscarriage

Complete miscarriage

This occurs when all the products of conception are passed from the womb. This type usually occurs before six to eight weeks of pregnancy or after 14-16 weeks, but rarely in the intervening period. If a complete miscarriage occurs, particularly after 14 weeks, the woman needs to be admitted to hospital for observation. Usually an ultrasound scan will be carried out to confirm that the womb is empty and that no further tissues remain inside. Where some tissue remains, evacuation of the retained products of conception (ERCP) will need to be carried out under general anaesthetic.

Threatened miscarriage

Occasionally a woman will bleed in pregnancy and have cramping pains without miscarrying, and will carry the baby to full term. This is not usually associated with any abnormalities later in the pregnancy or in the baby.

An inevitable miscarriage

Sometimes if a woman has been threatening to miscarry, the inevitable will occur, ie. the neck of the womb (the cervix) starts to dilate and open up. Once this occurs it is unlikely that the pregnancy will be preserved. Bleeding and pain are common symptoms of this. The pain is due to contraction of the womb as it tries to evacuate the pregnancy. Sometimes there can be nausea and vomiting. The woman may notice large pieces of tissue, which she might describe as pieces of liver, being passed from the vagina. This can be a very frightening experience. An inevitable miscarriage will either progress to an incomplete or a complete miscarriage. This situation usually requires hospital admission.

Incomplete miscarriage

Sometimes not all the products of conception are passed from the womb. This situation is called an incomplete miscarriage. Usually, when the woman is admitted to hospital an ultrasound scan will be carried out. If there are remains of tissue present in the womb then the woman will usually be taken to theatre for evacuation of retained products of conception. This is a short procedure taking approximately 20 minutes. Usually the woman will remain in hospital for a further 24 hours to observe bleeding loss.

Missed miscarriage

In this situation what happens is that the embryo fails to develop fully and, instead of being passed out of the womb in a miscarriage situation, it is retained inside. Usually the symptoms of pregnancy such as nausea and breast tenderness will disappear abruptly as the womb becomes progressively smaller. Often there is no bleeding, but occasionally the woman may notice a dark brown vaginal discharge. In this situation a series of ultrasound examinations need to be done to confirm that it is a missed miscarriage. There are two options of treatment in this situation. One is to allow nature to take its course and the woman will inevitably spontaneously miscarry within the next few weeks.

However this may not happen for several weeks, and it can be very distressing for a woman in this situation. Allowing nature to take its course may not be an acceptable option. The alternative is to carry out an evacuation of the womb. This is usually done in hospital under general anaesthetic. If the womb is larger than 12 weeks a drug called prostaglandin in the form of a vaginal pessary is inserted near the womb. This helps the woman to spontaneously expel the retained contents of the womb.

Occasionally, intravenous treatment may also be required. This process is completed by carrying out a curettage to ensure that no further tissue remains in the womb. If the womb is less than 12 weeks, evacuation of retained products of conception occurs under general anaesthetic.

Pregnancy test

A pregnancy test confirms the presence of a hormone called Human Chorionic Gonadotrophin (HCG) in the urine. A blood test will also check HCG levels. Often, after a miscarriage the pregnancy test can remain positive for a number of days as the level of circulating hormone is still quite high. However usually after a miscarriage the pregnancy test becomes negative in seven to 10 days.

Ectopic pregnancy

This situation occurs when the fertilised ovum implants outside of the womb, ie. in a tube or near an ovary. This condition is referred to as an ectopic pregnancy. Because the embryo will not survive outside of the womb, it is unfortunately inevitable that this type of pregnancy will not be viable (also, it can be a difficult condition to diagnose). Bleeding can often be very heavy and is a very serious event. An ectopic pregnancy is usually confirmed by ultrasound. Usually it means a laparotomy (operation in the abdomen) to remove the ectopic pregnancy from the tube. Occasionally it can be difficult to preserve the tube on the affected side.

Recurrent miscarriage

Recurrent miscarriage is diagnosed when there have been three consecutive pregnancies which end in spontaneous miscarriage. It is a very distressing situation and is poorly understood. Causes can include abnormalities of the uterine cavity, such as fibroids or intra-uterine adhesions. Cervical incompetence, where the cervix dilates and cannot retain the pregnancy, may also be a reason. Infections in the mother account for 15% of recurrent miscarriages. Abnormal development of the foetus and hormonal problems account for approximately 3%. Even though it can be a very depressing situation the probability of achieving a successful outcome in subsequent pregnancies is still more than 50%.

Causes of miscarriage

Problems in development of the foetus

Occasionally, minor abnormalities in the development of the foetus can occur. Sometimes the conception may fail to implant properly in the lining of the womb and not develop. Occasionally these errors in development are a result of a genetic problem. When miscarriage becomes recurrent, couples have investigations to rule out any genetic abnormalities, such as an abnormal chromosome pattern.

Hormonal causes

In the past it was thought that miscarriage was due to low levels of female sex hormones, and hormones such as oestrogen and progesterone were prescribed in the early stages of pregnancy, particularly in women with recurrent miscarriage. However this is difficult to prove, and giving hormone supplements to prevent miscarriage has not any strong scientific basis. However a hormone called Chorionic Gonadotrophin is important in maintaining early pregnancy and supplements of this are often used to prevent early miscarriage.

Sometimes a fibroid may be present and it distorts the cavity of the womb. This will interfere with implantation. Occasionally the cervix can be incompetent. This means it is unable to hold the contents of the womb. It dilates during the pregnancy, allowing the conceptus to be lost before full term is reached.

When this occurs a stitch can be put in place to stop the cervix opening prematurely. There are two kinds of stitch, one is called the Shirodkar and the other is called the McDonald. A stitch of this kind is inserted at around 14 weeks of pregnancy under general anaesthetic. In most cases this stitch is left in place until about 38 weeks of pregnancy.

Abnormal uterine shape

Occasionally the uterus may be an abnormal shape and this may increase the likelihood of miscarriage. This situation is believed to account for between 8%-30% of recurrent miscarriages. Another possibility is that the after-birth (placenta) may implant in a part of the womb, which has an inadequate blood supply.

Intrauterine adhesions

This is a rare condition. It is usually diagnosed during a procedure called hysteroscopy, where a dye is injected into the womb to outline the shape.

Subchorionic bleeding

Also called subchorionic hematoma. This is an accumulation of blood within the outer fetal membrane or the folds of the placenta. Most of these haematomas dissolve on their own but it is possible for the clot to cause a miscarriage.

Infection

If a woman becomes very ill in a pregnancy, miscarriage can occur. However there are certain bacteria and viruses which, if contracted in pregnancy are associated with a higher incidence of miscarriage. Rubella, chlamydia, cytomegalo and genital herpes are all associated with an increased risk of miscarriage.

An organism called toxoplasma, which is found in cat faeces, is also known to be associated with miscarriage. Women should not handle cat litter during pregnancy and should wear rubber gloves when doing gardening. Women who work on farms should avoid contact with sheep at lambing time. Listeria is an organism found in uncooked meats and unpasteurised cheeses. This is also a dangerous organism and women are advised to avoid these foods during pregnancy.

Immunology

The immune system helps our body defend us against harmful and foreign substances. It is the immune system that accounts for rejection of transplanted organs. In some ways and in some situations the woman's uterus sees the implanted foetus as foreign. When this happens a miscarriage will occur. This can often account for recurrent miscarriages. Treatment called immunotherapy to help reduce immunity is sometimes used, but is not often very successful.

Maternal diseases

Certain illnesses in the mother predispose her to miscarriage. Women who have diabetes which is poorly controlled have an increased risk of abnormality of the foetus and of miscarriage. Other conditions called SLE (Systemic Lupus Erithematosis) which is a condition related to arthritis, poses an increased risk of miscarriage, as does epilepsy. A rare condition called Wilson's disease is also associated with a higher risk of miscarriage.

Drugs and medication

Some drugs are known to cause miscarriage and birth defects. Migraine sufferers in particular, who have been using long term ergotamine drugs are thought to have an increased risk of miscarriage. Obvious treatments like those used for treating cancers and certain anaesthetic gases may also increase the risk of spontaneous miscarriage. Smoking and alcohol should be avoided in pregnancy.

Age

Women in their late 30s have a higher incidence of miscarriage than younger women. A reason for this may be the increased incidence of chromosomal abnormalities as women get older. Many of these abnormalities are called trisomies, Down's syndrome being the commonest. Many of the trisomy abnormalities result in early miscarriage.

Paternal causes

There is still a lot of research going on in this area. However, where the father has too many sperm (hyperspermia) or too few sperm, there may be an increased risk of miscarriage. This is thought to be due to decreased genetic content of the DNA in sperm in these situations.

Diet

All women should take folic acid pre-conceptually to reduce the chance of neural tube defects such as hydrocephalus and spina bifida. The important time to take folic acid is in the first six weeks of pregnancy, often before a women realises she is pregnant. Foetuses with these defects often miscarry in early pregnancy. Women with epilepsy are advised to take a higher dose of folic acid during pregnancy. The standard dose is 0.4mg. However women on antiepileptic drugs will need a higher dose, usually 5mg daily, because there is a higher incidence of neural tube defect in this group. A balanced diet of nutritious foods is recommended throughout pregnancy.

Injuries

Women are often concerned if they have any injuries in early pregnancy that it will result in miscarriage. In the early stages of pregnancy the womb is well protected by the pelvic floor and pelvic bones and the likelihood of miscarriage, even after a bad fall, is low. However, later in pregnancy the risk is higher. Road traffic accidents, especially in the latter half of pregnancy, are far more serious.

Psychological factors

Sometimes women feel, if they are very stressed or have emotional problems, that it increases the risk of a miscarriage. However there is no direct evidence to support this.

Grief

Miscarriage can be a very distressing time for many women and their partners. Emotions can vary from feelings of loss, loneliness and sadness to an overwhelming sense of grief and depression. Grief response after a miscarriage is very individual. Some women can experience profound feelings of loss. Their emotional response very much depends on the circumstances around the miscarriage.

It is well recognised by medical professionals that miscarriage can be extremely distressing, and help is available from GPs, midwives and obstetricians. Many women may blame themselves in some way for the miscarriage or may feel very angry. Counselling can help couples come to terms with what has happened and face the future. A small percentage of women may need antidepressant treatment.

Written by Dr Sinead Cotter, GP, Cork

Useful contacts

The Miscarriage Association of Ireland has branches in many counties throughout Ireland.

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