by Mr Daniel Stott
The word eclampsia comes from the Ancient Greek word éklampsis, meaning ‘a flash of light’. This was thought to relate to the sudden and dramatic onset of convulsions that can characterise severe disease.
But recent advances in pregnancy care mean that pre-eclampsia has gone from being sudden and unpredictable to being better anticipated, effectively screened for, and safely managed.
Predicting pre-eclampsia
Pre-eclampsia is a condition that is specific to the second half of pregnancy and can happen after 20 weeks’ gestation. It is diagnosed by a combination of new-onset hypertension in pregnancy and evidence of kidney problems (typically with protein in the urine), liver problems or placental problems (which may be evident by ultrasound investigation slowing of the baby’s growth).
There’s new evidence that screening for pre-eclampsia risk, early in pregnancy, is effective and can improve pregnancy outcomes. Modern individualised screening for pre-eclampsia consists of taking a detailed medical history in the first trimester, scanning the pressure in the uterine arteries that supply the placenta, and measuring the level of placentally-produced hormones with a simple blood test. Combining the results of these investigations can help identify, at an early point in pregnancy, those women who are most at risk of developing pre-eclampsia later in the pregnancy. This method of individualised screening for pre-eclampsia is now available in many UK hospitals.
Preventing pre-eclampsia
The main advantage of identifying women who are most at risk of developing pre-eclampsia is that it empowers those women to access effective prophylaxis against the disease. New evidence shows that aspirin, at a daily dose of 150mg, given to women who are at high risk, reduces the risk of pre-term pre-eclampsia by more than 50%. Aspirin improves the function of the placenta and is safe in pregnancy. It is the single most effective way of reducing pre-eclampsia risk and it should be taken from early in pregnancy.
Prognosticating pre-eclampsia
Another important advance in pre-eclampsia care has been the introduction, over the past five years, of so-called biomarker testing. These new blood tests can measure placentally-produced proteins and reliably predict the onset and course of pre-eclampsia. There is good evidence that these tests can help both speed up the diagnosis of pre-eclampsia in women with symptoms and they anticipate how severe it is likely to become. These tests can therefore play an important role in safely determining how often women need to be reviewed in clinic, how often they should have scans, or whether they should be admitted for inpatient care.
Post-diagnosis management of pre-eclampsia
The mainstay of managing pre-eclampsia remains controlling the maternal blood pressure. There is good and recent evidence that tight blood pressure control is associated with better outcomes in pre-eclampsia. Labetalol or nifedipine (and sometimes both) are common oral medications that are used to lower blood pressure in pregnancy. Sometime intravenous medications are needed to control the blood pressure if there is severe hypertension, and magnesium sulphate is sometimes used to lower the risk of seizures in severe pre-eclampsia.
As well as careful monitoring of the maternal blood pressure, it’s important to regularly check the kidney function, liver function and clotting function. These can all be adversely affected in pre-eclampsia.
Because pre-eclampsia can also impair the function of the placenta it’s important to carry out regular ultrasound surveillance of the baby’s growth. Fetal wellbeing can be monitored on scan not only by measuring the growth of the baby, but also be looking at blood flow studies around the baby (Doppler studies).
In circumstances either where the placental function is becoming very impaired or where there are concerns about how the mother is being affected by pre-eclampsia, delivery may be recommended.
Planning delivery in pre-eclampsia
Because pre-eclampsia is a pregnancy-specific condition, delivery is effectively cures pre-eclampsia. Normally the blood pressure will start to settle in the days after delivery, but anti-hypertensive medicines are usually continued initially after the birth.
When to plan for delivery is of the utmost importance in the safe management of pre-eclampsia. Delivery may be prompted by worsening maternal symptoms or signs of kidney or liver problems or by placental dysfunction evident on scan with problems like fetal growth restriction.
There is recent trial evidence that in pregnancies complicated by pre-eclampsia, there is likely to be very little difference in outcomes for babies delivered after 34 weeks compared to those delivered at term. Outcomes for mothers are likely to be slightly better with earlier delivery compared to ongoing management after 34 weeks of pregnancy. National guidance states that when pre-eclampsia is diagnosed after 37 weeks of pregnancy, delivery should be recommended.
Postpartum pre-eclampsia
There’s emerging strong evidence that women who have had pre-eclampsia are at an increased risk of cardiovascular problems (such as chronic hypertension) later in life. Therefore it’s important to try and keep to a healthy lifestyle with good diet and exercise. Entering a subsequent pregnancy with a normal BMI significantly lowers the risk of pre-eclampsia recurring.
From being a bolt from the blue for the ancient Greeks, the advances of modern medicine have meant that pre-eclampsia can now be mapped, monitored and managed effectively.