Pre-eclampsia
Introduction: Understanding Pre-Eclampsia
What is pre-eclampsia?
Pre-eclampsia is a condition that affects 3-5% of pregnancies and, worldwide, is responsible for more than 42,000 maternal deaths each year. For every tragic loss, 50-100 women experience serious health issues due to this condition.
Who is most affected?
Pre-eclampsia mainly affects women in low-income and middle-income countries, where medical resources and access to proper care might be limited. But it can occur anywhere and may present in different ways. In developed countries like Australia, pre-eclampsia can still cause medical problems, lead to preterm birth and – more rarely – have severe consequences.
Symptoms and diagnosis
Symptoms like breathlessness, vomiting, severe abdominal pain, and significant placental problems may sometimes occur. Other times, a woman might not show any signs but is found to have high blood pressure during a routine check-up. Eclampsia is when a woman has seizures.
Treatment approaches
Currently, there's no cure for the progression of pre-eclampsia, but it can be managed. If diagnosed early in pregnancy, careful planning and monitoring can help ensure the best possible outcomes for both mother and baby. Research in recent years has provided valuable insights into preventing pre-eclampsia, diagnosing it accurately, and choosing the best time to plan birth.
Diagnosis and clinical definition: What is pre-eclampsia
This section provides an update on managing pre-eclampsia, focusing on the latest evidence to help improve care and pregnancy outcomes.
Understanding the condition
Pre-eclampsia is a complicated disease that evolves during pregnancy and affects multiple organs. It usually starts as high blood pressure with other issues like protein in the urine and can affect organs like the brain, liver, kidneys, blood system, lungs, and placenta. Sometimes, these other organs are affected before high blood pressure happens. Some variations of pre-eclampsia spectrum disorder don’t have high blood pressure.
How is it diagnosed?
Doctors look for signs like high blood pressure, severe headaches, visual disturbances, pain in the upper abdomen, and more. Blood pressure is ideally measured using a manual machine for screening purposes, and proteinuria (protein in the urine) can be detected using simple tests. Even though a 24-hour urine collection was previously considered the best way to detect proteinuria, quicker and more reliable alternatives are now available.
What happens if it's diagnosed late?
Diagnosing pre-eclampsia late can be challenging, especially in cases where no medical history is available or where high blood pressure or kidney disease already existed before pregnancy. Guidelines recommend close monitoring or hospital admission if severe features appear.
If you or someone you know may be at risk for pre-eclampsia, seeking professional medical advice and regular check-ups are crucial. Understanding and managing pre-eclampsia can make a significant difference in ensuring a healthy pregnancy for both mother and baby.
Risk factors: What increases the risk of pre-eclampsia?
Understanding the risk factors for pre-eclampsia can help in early detection and better management. Let's look at what can make someone more prone to this condition.
1. History of pre-eclampsia:
If you have had pre-eclampsia, you're at a higher risk, around eight times more likely to experience it again.
The risk might be lower if you had pre-eclampsia in your first pregnancy but not in subsequent pregnancies.
A history of preterm pre-eclampsia means you may have a 25-30% chance of the condition recurring.
2. Chronic hypertension:
Having long-term high blood pressure increases the risk of pre-eclampsia by five times.
3. Previous pregnancy complications:
If you've had problems like fetal growth restriction, stillbirth, or abruption in past pregnancies, these may increase your risk, showing how closely pre-eclampsia can be linked to placental issues.
4. Lifestyle and health factors:
Some risks can be reduced with lifestyle changes and proper medical care:
Weight Management: Keeping a healthy weight before pregnancy.
Avoiding Certain Fertility Treatments: Reducing the chance of having multiple babies at once, as this can increase risk.
Understanding Age-Related Risks: Being aware that older maternal age can affect pregnancy outcomes.
Managing Chronic Medical Conditions: Treating conditions like lupus and chronic hypertension effectively can help reduce the risk of pre-eclampsia.
If you or someone close to you fall into any of these categories, it doesn't mean pre-eclampsia is certain, but being aware of these factors and discussing them with your healthcare provider can lead to closer monitoring and potentially better outcomes.
Pre-eclampsia: How does it develop?
Pre-eclampsia is a complex condition that can be difficult to understand. I'll break down the development of pre-eclampsia into key stages to provide an overview.
1. Normal early pregnancy:
In a normal pregnancy, the placenta adapts the uterine blood vessels to facilitate oxygen and nutrient exchange. This is called blood vessel remodelling.
The ends of these vessels remain wide open, creating a ‘high flow’ system to ensure the baby receives plenty of blood.
2. Impaired placenta remodelling:
In some women who develop pre-eclampsia, this blood vessel remodelling is impaired.
This can result in under-perfusion (lack of blood flow), oxidative stress, and inury to the placenta.
In medical terms, this condition has been defined as ‘maternal vascular malperfusion’ and is found to link directly with the severity of pre-eclampsia.
3. Immune system's role:
Immune mismatches between parents' genes may be a factor, but research hasn’t established how this information can be useful in practice.
Abnormal interactions between certain cells in the early first trimester might increase the risk of developing pre-eclampsia.
4. Second-trimester changes:
As pregnancy progresses, the affected placenta secretes increased blood factors that can lead to inflammation and injury to blood vessels.
This leads to high blood pressure and harm to various organs, like the kidneys, liver and placenta.
5. Risk factors and connections:
Poor placental implantation explains why fetal growth restriction is linked with pre-eclampsia.
Immune factors may explain why first pregnancies are a risk factor.
Increased placental size can lead to pre-eclampsia, for example, in twin pregnancy.
Women over 40 and those overweight, diabetic, or with chronic high blood pressure are more susceptible.
Conclusion
Understanding how pre-eclampsia develops means recognising the two-stage paradigm of poor placental development followed by the effect on broader body systems. As you can see, this is a complex condition. There are interactions between genetic, immunological, and environmental features. Research insights into these underlying causes may lead to better preventive options and treatments in the future.
Understanding predictive and diagnostic tools for pre-eclampsia
Researchers are working on ways to predict who might develop this condition and diagnose it quickly. This helps manage the condition better and reduces risks to both mother and baby.
Screening Methods:
Clinical risk factors include the patient's medical history, age, and other factors that might indicate a higher chance of developing pre-eclampsia.
Blood tests (biomarkers): Tests on the mother's blood can reveal substances that might signal a risk of pre-eclampsia.
Uterine artery Doppler flow analysis: This special ultrasound examines the blood flow in the uterus and can help in the prediction.
A combination of these methods is used to create an algorithm or set of rules that helps predict the likelihood of pre-eclampsia. Sometimes, a simple aspirin treatment can be prescribed to those at higher risk.
Predicting and diagnosing pre-eclampsia is a vital part of antenatal care. The combination of clinical risk factors, blood tests, and ultrasound shows promise in predicting who might develop this serious condition. However, challenges and limitations still need to be addressed, and ongoing research will undoubtedly clarify these. If you're pregnant or planning a pregnancy, it may be helpful to discuss these screening options with your healthcare provider to understand what might be right for you.
Using aspirin to prevent pre-eclampsia
Aspirin is one preventive treatment that shows promise in preventing pre-eclampsia. This section will discuss how aspirin helps, its effectiveness, the recommended dosage, and some considerations to remember.
Why use aspirin?
Low-dose aspirin is the only drug treatment for pre-eclampsia supported by strong evidence. Research suggests that taking aspirin daily from the end of the first trimester until 36 weeks can reduce the risk of developing pre-eclampsia by around 18%. Aspirin doesn’t prevent late-onset pre-eclampsia when the condition develops after 37 weeks.
How does It work?
The exact way aspirin prevents pre-eclampsia is still unclear. Some theories include:
Improving placental implantation early in pregnancy.
Protecting maternal blood vessels by affecting certain chemicals in the body.
How to identify who needs aspirin?
Screening methods help identify those at higher risk of pre-eclampsia, such as those with specific risk factors.
Recommended doses
Most guidelines recommend 75–100 mg of aspirin daily.
Some research supports using 150 mg for specific screening methods, but evidence is limited.
A large trial showed that 81 mg of aspirin daily starting during the first trimester effectively reduced risks, especially in lower-income countries.
When to start?
National guidelines often recommend starting aspirin before 16 weeks gestation, but evidence shows it may still be effective if started later, up to 22 weeks.
Possible risks
Aspirin might be associated with a small risk of bleeding during and after childbirth. Such risks should be weighed against potential benefits.
Aspirin has shown promise in preventing pre-eclampsia, and specific guidelines have been developed for its use. How it works, optimal timing and dosage are still under research. However, aspirin's potential benefits in reducing pre-eclampsia risks, particularly in specific groups like first-time mothers in lower-income countries, are promising.
If you are pregnant or planning to become pregnant and have concerns or questions about pre-eclampsia, discussing aspirin use with your healthcare provider might be helpful. It can be tailored to your situation, weighing the benefits against any potential risks.
Long-term health effects of pre-eclampsia
Pre-eclampsia is a condition during pregnancy that affects some women and can cause serious health issues. Understanding its long-term consequences can help you be better prepared to maintain a healthy lifestyle after a pregnancy affected by pre-eclampsia.
Large studies have shown that women with a history of pre-eclampsia may face higher risks of certain health issues later in life. When we talk about risks and increases in risk, remember that these relate to the chance of something happening. It doesn’t mean that it will happen or necessarily even likely to.
If a condition was going to occur, say 1-in-100 times, a 2 times higher risk means that it will now happen 1-in-50 times. Relative risks don’t tell you if you’ll be affected but give you a guide compared to the chance of something happening. Two times higher risk of something rare is still rare.
Heart-Related Problems:
4 times higher risk of heart failure.
2.5 times greater risk of coronary heart disease.
1.8 times greater risk of stroke.
2.2 times higher risk of death from heart-related diseases.
Blood Pressure Issues:
4.5 times greater risk of chronic high blood pressure, often seen within 10 years of pregnancy.
Diabetes:
Higher chance of developing diabetes, even if gestational diabetes was not present during pregnancy.
Kidney Conditions:
5 times higher risk of severe kidney disease.
Neurological Conditions:
3 times greater risk for vascular dementia and potential issues with perception, memory, and motor function.
These risks are often more pronounced if pre-eclampsia was severe, happened in more than one pregnancy, or the baby was born early.
What Can Be Done?
The exact reasons for these increased risks are still being researched, but it is believed that pre-eclampsia may cause lasting changes in the body. This can increase the likelihood of developing chronic diseases.
If you have had pre-eclampsia, it's essential to maintain a healthy lifestyle and get regular check-ups for blood pressure and possibly diabetes. Starting these measures soon after pregnancy may help reduce future health risks, although more research is needed to understand the best interventions.
The American Heart Association now recognises pre-eclampsia as a major risk factor for heart disease, underscoring its importance in long-term health planning.
So, in summary, pre-eclampsia doesn't only affect your health during pregnancy; its effects can linger and lead to serious health concerns later. Understanding these risks and taking proactive steps can help you manage your health in the long term.
There's much to be hopeful about in the fight against preeclampsia and eclampsia. But there's also much research to be done. If you or someone you know is pregnant, remember that awareness and early intervention are key. Always consult with healthcare professionals for personalised care and advice.
Dr Danny Tucker
Table from Chappell et al. Pre-eclampsia Seminar. Lancet 2021