Miscarriage: overview

What is miscarriage?

Miscarriage is a pregnancy that ends spontaneously before 20 weeks. After the 20th week of pregnancy the loss of a fetus is called a stillbirth.

Miscarriage is very common. In fact, it has been estimated that up to half of all pregnancies end in an early miscarriage that occurs before the first period would have been missed, when most women do not yet know they are pregnant. Of pregnancies that make it past this point, up to 15 per cent result in a miscarriage, mostly during the first trimester. Sometimes your doctor or nurses may refer to your miscarriage as a spontaneous abortion. Abortion is the common medical name for all pregnancies that end before 20 weeks — both miscarriages and terminations.

Why does miscarriage occur?

Most miscarriages occur because something went wrong during or soon after conception. There are thought to be many reasons behind this. Here is a list of some reasons.

  • In many cases the part of the pregnancy that grows into the baby fails to develop. This may be due to genetic abnormalities in the baby's cells.
  • The fertilised egg may not attach itself to the wall of the uterus or attaches in the wrong place.
  • The mother's body may not make enough of the hormones that support a pregnancy, such as progesterone.
  • Something may be wrong with the placenta.
  • The mother’s immune system may reject the placenta.
  • The mother may have an underlying medical condition, such as uncontrolled diabetes, a thyroid problem, or a tendency towards blood clots.
  • She may have a deformed uterus or a weak cervix.
  • Exposure to some environmental chemical pollutants, including cigarette smoke, can increase the risk of miscarriage.
  • The risk of miscarriage increases with age and with the number of previous pregnancies.

What happens during a miscarriage?

Symptoms differ depending on how advanced the pregnancy was and what caused the miscarriage. Threatened miscarriage may be experienced days or even weeks before you lose the baby, however, a threatened miscarriage does not always end in miscarriage. At this stage you may experience any of the following symptoms:

  • light vaginal bleeding;
  • vaginal discharge;
  • pain similar to period pain (uterine cramps); or
  • no longer ‘feeling’ pregnant, for example, the tender breasts and nausea associated with pregnancy may disappear.

If you have any of these symptoms, talk to your doctor. In many of these cases the symptoms settle down and the pregnancy continues as normal.

In miscarriage the cervix opens, and part or all of the contents of the uterus come away and pass out of the vagina. There are several common signs of miscarriage.

  • Bleeding becomes heavy.
  • Pain is like bad period pain or birth contractions.
  • Faintness and nausea.
  • You pass pieces of placenta which look like blood clots or pieces of raw liver.
  • You may see the fetus. If you are more than 4 months pregnant, the fetus may be alive.

An incomplete miscarriage occurs when some pregnancy tissue remains inside the uterus. You may need to have a dilatation and curettage (D & C) or vacuum aspiration operation after an incomplete miscarriage due to the risk of infection developing from tissue remaining in your uterus. For this you will usually be given a general anaesthetic, your cervix opened and uterus completely emptied. Once the uterus is empty again the miscarriage is complete. The cervix closes, pain stops and bleeding slows down.

Ectopic pregnancy

An ectopic pregnancy is one in which the fetus is growing in the wrong place, usually in one of the fallopian tubes. As the fetus gets bigger, it may cause the fallopian tube to stretch, bleed or rupture. This can cause massive bleeding and infertility, and can be life-threatening. These problems typically occur when the pregnancy is 6 to 7 weeks along, but can occur anywhere from 4 to 10 weeks.

If your doctor is at all suspicious of an ectopic they will either admit you to hospital or organise special tests such as an ultrasound and blood tests measuring the amount of the pregnancy hormone beta HCG in your body.

Contact your doctor immediately if you have any of the following symptoms as your life may be in danger and you may need an urgent operation:

  • vaginal bleeding and cramping pain shortly after a late period;
  • gradual bleeding causing pain and/or pressure in the lower abdomen;
  • sudden, severe pain in the lower abdomen;
  • bad pains that do not feel like period pains;
  • dark bleeding which starts after the pain; or
  • faintness, nausea, dizziness and vomiting.

What should I do if I think I am miscarrying?

  • Ring your doctor or local hospital and describe your symptoms. Remember, your doctor cannot prevent miscarriage.
  • Ask your partner, a friend or relative to stay with you, preferably someone with a driver’s licence and car who can take you to the doctor or hospital if necessary.
  • Soak up the blood with sanitary pads or towels. Keep a record of how many pads you go through each hour and how heavily stained they are. Lie down if you are bleeding very heavily.
  • Pack an overnight bag for hospital, just in case you need it later.
  • If you need a D & C, do not eat or drink. Your stomach must be empty if you are going to have an anaesthetic. Check this with your doctor.
  • Save everything you pass in a bowl or bucket (rather than sitting on the toilet) to be seen by the doctor or tested to see why your miscarriage happened. If there was a small fetus, you can save it for burial. In some cases there is not a fetus or it is simply too small to find.
  • If you are alone and things are happening fast, dial 000 and ask for an ambulance. Never drive yourself to hospital if you are having a miscarriage.
Last Reviewed: 08 July 2009
myDr. Adapted from original material sourced from MediMedia.
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