Vaginal bleeding that occurs after the 20th week of pregnancy and before the onset of labour is referred to as antepartum haemorrhage and should always be reported to your doctor or midwife. The bleeding may be similar to a normal menstrual period but may also be lighter or heavier.

Some women confuse antepartum haemorhage with a 'show' (blood-stained mucus secretions that occur due to the stretching of the cervix and that usually appear before the beginning of labour).

Should I go to hospital?

Antepartum haemorrhaging, even if it is mild, normally requires admission to hospital for tests and observation. Your baby's heartbeat will be monitored and an ultrasound scan will be taken to determine the location of your placenta and to investigate whether or not it has separated from the wall of the uterus. You will also have a number of blood tests.

If the bleeding settles and you and your baby are in satisfactory health you may be discharged from hospital. However, both of you will continue to be assessed until you give birth.

If the haemorrhaging continues, however, you may have to remain in hospital on bed rest until your baby is born. Where the bleeding becomes severe it may be necessary to deliver your baby early due to the risk of oxygen deprivation. In such circumstances a caesarean section is likely.

Following a severe antepartum haemorrhage some women require a blood transfusion.

What are the causes of bleeding?

Minor trauma
Bleeding may be due to minor local problems involving the cervix such as a cervical erosion or polyp. Light bleeding sometimes occurs following sexual intercourse or a cervical exam and is rarely anything to worry about. However, bleeding can also be caused by more serious problems affecting the placenta including placenta praevia or placenta abruption. Both of these conditions are potentially life-threatening to the woman and her baby and need to be investigated.

Placenta abruption/separation
Placenta abruption is the partial or complete premature separation of a normally situated placenta from the wall of the uterus after the 22nd week of pregnancy. Blood builds up in the empty space created by the separation and often, but not always, it will leak into the vagina. It is classified as mild, moderate or severe depending on the amount of blood loss and the degree to which the placenta has separated.

Placenta abruption occurs in about 1% of pregnancies. The cause remains unclear but it is often associated with women who have hypertension or pre-eclampsia. It may also occur when there is a sudden reduction in uterine size, which can result following the delivery of the first twin or loss of copious amounts of amniotic fluid, for example. Rarely, direct trauma to the abdomen may partially dislodge the placenta.

The mildest type of placenta abruption is relatively pain free, although you may experience slight localised pain. In the majority of cases there is only a small amount of blood loss, the degree of placenta separation is minor and the baby is not affected. If mother and baby are both stable the condition is usually managed with admission to hospital and bed rest.

If there is no further bleeding you may be allowed home following an ultrasound scan that confirms that the placenta is not low-lying. If you have passed the 37th week of pregnancy your labour may be induced. Further bleeding or evidence that the baby is distressed may necessitate a caesarean section.
In more severe cases where the bleeding is internal, pain and signs of shock may be the only symptoms. In approximately one third of cases the placenta surface separates and the baby's oxygenation is compromised and this can be fatal for the baby.

Severe cases of placenta abruption causing severe shock, blood clotting problems or kidney failure are managed with rapid blood transfusion and immediate delivery of the baby by caesarean section.

Placenta praevia
Placenta praevia means that the placenta is partially or wholly situated in the lower segment of the uterus near the birth canal and is therefore completely or partially covering the cervix. Placenta praevia can cause severe bleeding either in the last trimester or when the cervix begins to open at the beginning of labour.

This condition occurs in approximately 0.5% of pregnancies and is a potentially dangerous condition for both the woman and her baby. It is more common in women who have had a previous pregnancy, those who have had a previous caesarean section and those who have had a previous placenta praevia.

Placenta praevia often has no symptoms and is frequently diagnosed at a routine ultrasound scan. It is graded or typed depending on the amount of placenta that lies close to or covers the cervix. The more placental tissue that covers the cervix the higher the chances of bleeding before or during delivery.

Minor degrees of placenta praevia - graded as type 1 or type 2 - may not adversely affect the pregnancy and a vaginal delivery is possible. If bleeding is very slight and there are a number of weeks to go before the baby is born bed rest and observation in hospital may be all that is required.

More serious degrees of placenta praevia graded as type 3 or 4 may give rise to sudden unexpected painless vaginal bleeding in late pregnancy a blood transfusion may be necessary and delivery of the baby by immediate caesarean section is required.