Pre-eclampsia

Pre-eclampsia is a serious disorder of pregnancy characterised by high maternal blood pressure, protein in the urine and severe fluid retention. It is quite common, affecting around five to 10 per cent of all pregnancies in Australia. One to two per cent of cases are severe enough to threaten the lives of both the mother and her unborn child.

Pre-eclampsia accounts for one in five inductions and one in six Caesarean sections. The mechanisms behind the condition are mysterious, but genetic factors and the placenta seem to play significant roles. For reasons unknown, pre-eclampsia tends to be more common in first rather than subsequent pregnancies. The mother’s blood pressure usually returns to normal as soon as the baby is delivered.

Features of pre-eclampsia include high blood pressure, the appearance of protein in the urine, and generalised swelling of bodily tissues. Pre-eclampsia can effect many parts of the body, including the brain, heart, kidneys, blood cells, clotting systems, and the placenta. When it affects the placenta, the baby’s growth and health may be compromised. One particularly feared complication of pre-eclampsia is eclampsia, which is the name given to generalised convulsions associated with this disorder. Each year, 50,000 women die world-wide from eclampsia alone. In Australia, although deaths during pregnancy are rare, pre-eclampsia and its complications are a major cause of maternal and perinatal mortality.

Pre-eclampsia only occurs during pregnancy. It usually arises in the second half of pregnancy and is more common in first pregnancies. In its milder forms, it can complicate as many as one in ten pregnancies. Its severer forms can affect one in every hundred pregnancies.

The only known cure for pre-eclampsia is ending the pregnancy, which may mean that a baby needs to be delivered prematurely for the sake of the mother’s health, despite the fact that such a delivery may jeopardise the baby’s welfare.

Pre-eclampsia is a particularly sinister disease because in its early stages a woman may be totally unaware of its presence. It is only by taking a blood pressure measurement and testing the urine for the presence of protein that the presence of the disease may be revealed. The detection of pre-eclampsia is therefore one of the most important reasons for regularly attending a doctor for medical check-ups during pregnancy.

When pre-eclampsia occurs, many women find it hard to accept the diagnosis. This is because they may feel quite well in themselves and because they may initially believe that such a complication could not possibly trouble their pregnancy. Many women also find it difficult initially to deal with the change in expectations involved, when what they hoped would be a normal, healthy pregnancy suddenly becomes complicated by a serious disease which threatens not only their own health but also that of their unborn baby. Suddenly, much modern medical technology becomes necessary to improve the welfare of both mother and baby. Many tests are required to check on the progress of the disease. Many drugs may be necessary to improve the health of both mother and baby and to slow the progress of the disorder. Inevitably, delivery will be necessary, often either by labour induction or by Caesarean section. It is not uncommon for both the mother and the father to be very confused or frightened by such a turn of events. The father may feel quite powerless and unable to provide the support and assistance he had anticipated being able to give during the course of a normal labour and delivery.

For these reasons, it is important that when the medical emergency has been dealt with, there be an opportunity for a couple to spend time with their doctor so that explanations can be given and questions answered in an unhurried fashion.

Unfortunately, the cause of pre-eclampsia is as yet unknown. It is thought that the fault may lie with a deficient attachment of the placenta to the womb and this may have a genetic basis in many cases.

The possibility is currently the subject of intense research, because it is hoped that a clearer understanding of what causes pre-eclampsia may allow the development of logical treatments to either prevent it occurring or cure it when it does occur.

Fortunately, most women who suffer from pre-eclampsia in their first pregnancy are not troubled by it in subsequent pregnancies, or if they are, it recurs in a milder way. Women who have suffered from severe early onset pre-eclampsia may benefit from taking low-dose aspirin in their next pregnancy to help prevent a recurrence of the disease.

When severe pre-eclampsia does occur, it is usually necessary to lower high blood pressure with anti-hypertensive medication and to prevent eclampsia with anti-convulsant medication. Because pre-eclampsia does not usually resolve immediately upon delivery, these therapies may need to be continued for several days at least after the baby is born.