What are pre-eclampsia and pregnancy-induced hypertension?
Pre-eclampsia and pregnancy-induced hypertension are the most common blood pressure problems in pregnancy. They can only occur in pregnancy and will resolve within a few weeks or months of delivery. They represent two forms of the same disorder. When the high blood pressure is combined with abnormally high levels of protein in the urine, this is called pre-eclampsia. The protein in the urine indicates that the kidneys are upset by the condition indicating that the condition is severe regardless of how severe the high blood pressure is. Where pregnancy hypertension occurs without proteinuria, then this is termed pregnancy-induced hypertension or PIH for short. The level of high blood pressure is usually divided into mild - moderate hypertension (diastolic blood pressure 90 - 110mmHg) or severe (diastolic blood pressure greater than 110mmHg). It is not just the blood pressure and kidneys that are upset in these conditions the liver can sometimes be upset and occasionally the blood clotting system will be disturbed.
How common are pre-eclampsia and pregnancy-induced hypertension?
Pregnancy-induced hypertension occurs in up to around 5-10% of pregnancies although many of these cases are mild. Pre-eclampsia occurs around 2% of pregnancies.
What are the features of pre-eclampsia?
The classic features of pre-eclampsia are high blood pressure, protein in the urine (proteinuria), and swelling of the legs fingers and face (oedema). It usually occurs in the second half of pregnancy. Once it occurs, it progresses at a variable and unpredictable rate until delivery. Until it is very severe it has no symptoms. You may feel entirely well even though you have this problem. This is a major reason to attend for antenatal care so that this problem can be identified, as untreated it can be dangerous for both you, the mother, and the baby. In its most severe forms you may have headache, see flashing lights and have blurred vision, have pain below your rib cage in your abdomen and sometimes vomit. One of the worst forms is eclampsia when convulsions (fits) occur due to the brain being upset by the condition.
What causes pre-eclampsia?
The cause of pre-eclampsia is unknown. The primary problem appears to be abnormal implantation of the afterbirth into the mother's womb. Doctors don't really understand why this problem with the afterbirth occurs. But it triggers a whole cascade of problems that upset the function of the blood vessels resulting in high blood pressure. These changes also lead to leaky blood vessels allowing fluid to collect in the tissues causing the characteristic swelling. Abnormal clotting in tiny blood vessels can also occur. These changes can upset the function of organs such as the kidney and liver and occasionally the brain. Thus, pre-eclampsia is not simply a high blood pressure problem, rather it can affect every organ and system in the body due to widespread disturbance in the function of the blood vessels.
Am I at risk of pre-eclampsia?
Any pregnant woman can get pre-eclampsia. Some women are more vulnerable than others. Doctors have now identified many risk factors that place you at higher risk of having pre-eclampsia. Pre-eclampsia has been traditionally regarded as a problem seen in your first pregnancy. This is not strictly true as it is the first pregnancy to your partner that is at risk. If you have had a previous pregnancy to your partner and you did not get pre-eclampsia, you are unlikely to get pre-eclampsia in a future pregnancy with the same partner. The risk of pre-eclampsia is also increased with pre-existing medical conditions such as kidney disease or diabetes. In addition, there is a familial or genetic component to pre-eclampsia, if your mother or sister had pre-eclampsia then you will have a slightly higher risk of developing pre-eclampsia.
Can my baby be affected by pre-eclampsia?
The baby can be affected because of the afterbirth not embedding properly into your womb. This can result in so called placental insufficiency that can impair the baby's growth or lead to premature delivery.
How do Doctors diagnose pre-eclampsia?
At every antenatal check Doctors look for high blood pressure and protein in the urine to identify pre-eclampsia and pregnancy induced hypertension