What is pre-eclampsia? 

Pre-eclampsia is a condition that affects some pregnant women, usually during the second half of pregnancy (from 20 weeks) or soon after their baby is born. While most pregnancies proceed without complication, pre-eclampsia is a serious condition that can lead to life-threatening issues if not monitored and treated. In the UK, it is a primary focus of antenatal care, with midwives and doctors checking blood pressure and urine at every appointment. Understanding the signs of pre-eclampsia allows for early intervention, which is key to a healthy outcome. 

What We’ll Discuss in This Article 

• The clinical definition of pre-eclampsia and when it typically occurs. 

• Common symptoms and ‘red flags’ that require immediate attention. 

• How the condition affects the body of the mother and the baby. 

• The underlying clinical causes related to placental development. 

• Risk factors and triggers that increase the likelihood of the condition. 

• Differentiation between pre-eclampsia and other forms of pregnancy hypertension. 

Understanding Pre-Eclampsia and Its Health Risks 

Pre-eclampsia is a multi-system pregnancy disorder characterised by high blood pressure (hypertension) and the presence of protein in the urine (proteinuria). It affects the mother’s kidneys, liver, and brain, and can restrict the baby’s growth by limiting blood flow through the placenta. While most cases are mild, it can progress to eclampsia (seizures) if left untreated. 

Clinically, pre-eclampsia is diagnosed when a woman with previously normal blood pressure develops a reading of 140/90 mmHg or higher after 20 weeks of pregnancy, accompanied by protein in the urine. Because it can be ‘silent’ in its early stages, regular screenings are vital. In the UK, if you are at high risk, your clinical team may recommend taking low-dose aspirin daily from 12 weeks of pregnancy to help prevent the condition from developing. 

Symptoms and ‘Red Flags’ 

The symptoms of pre-eclampsia can often be mistaken for common pregnancy discomforts, such as swelling or headaches. However, in pre-eclampsia, these symptoms are often sudden and severe. Recognising these ‘red flags’ is essential, as they indicate that the condition is affecting the mother’s vital organs and that immediate medical assessment is required to prevent complications. 

Symptoms to watch for include: 

• Severe Headache: A persistent, throbbing headache that does not improve with paracetamol. 

• Vision Disturbances: Including blurring, flashing lights, or seeing ‘floaters’ or spots. 

• Sudden Swelling (Oedema): Particularly sudden puffiness in the face, hands, or feet. 

• Pain Under the Ribs: Severe pain just below the ribs, usually on the right side (liver area). 

• Nausea and Vomiting: If it begins suddenly in the second half of pregnancy. 

• Feeling Unwell: A general sense of being ‘not right’ or excessively breathless. 

Causes of Pre-eclampsia 

The exact cause of pre-eclampsia is not fully understood, but it is widely believed to begin with the placenta—the organ that connects the mother’s blood supply to the baby. If the blood vessels in the placenta do not develop correctly during early pregnancy, they become narrow and fail to respond properly to hormonal signals, causing the mother’s blood pressure to rise as the body tries to force more blood to the baby. 

Clinical causes include: 

• Placental Ischaemia: Reduced blood flow and oxygen to the placenta, which releases proteins into the mother’s bloodstream. 

• Vascular Inflammation: The proteins from the placenta trigger a widespread inflammatory response in the mother’s blood vessels. 

• Kidney Damage: The inflammation causes the kidneys to ‘leak’ protein into the urine, which is a hallmark sign of the condition. 

• Abnormal Immune Response: A theory that the mother’s immune system reacts abnormally to the placenta. 

Triggers and Risk Factors 

Certain factors can act as triggers or indicators that a woman is more likely to develop pre-eclampsia. In the UK, midwives categorise these into ‘high-risk’ and ‘moderate-risk’ factors. If you have one high-risk factor or two moderate-risk factors, it triggers a clinical recommendation for preventative treatment and more frequent monitoring throughout the pregnancy. 

High-risk factors include: 

• Previous Pre-eclampsia: Having had the condition in a previous pregnancy. 

• Chronic Kidney Disease: Pre-existing issues with kidney function. 

• Autoimmune Diseases: Such as lupus or antiphospholipid syndrome. 

• Pre-existing Hypertension: High blood pressure that existed before the pregnancy. 

• Diabetes: Having Type 1 or Type 2 diabetes. 

Moderate-risk factors include: 

• First Pregnancy: Or a gap of more than 10 years since the last baby. 

• Maternal Age: Being 40 years of age or older. 

• BMI: Having a Body Mass Index (BMI) of 35 or more at the start of pregnancy. 

• Family History: Having a mother or sister who had pre-eclampsia. 

Differentiation: Gestational Hypertension vs. Pre-eclampsia 

It is important to differentiate between gestational hypertension and pre-eclampsia, as the management and risk levels vary significantly. While both involve high blood pressure developing after 20 weeks of pregnancy, pre-eclampsia is a more complex, ‘multi-system’ condition that involves other organs, most notably the kidneys. 

• Gestational Hypertension: High blood pressure after 20 weeks without protein in the urine. It is generally less severe but must be monitored as it can progress to pre-eclampsia. 

• Pre-eclampsia: High blood pressure with protein in the urine (or other organ involvement). This requires much closer hospital-based monitoring. 

• Eclampsia: A severe complication of pre-eclampsia involving seizures; this is a life-threatening emergency. 

• HELLP Syndrome: A rare but severe variant of pre-eclampsia involving liver damage and blood clotting issues. 

Conclusion 

Pre-eclampsia is a serious condition that requires vigilant monitoring by both the patient and the healthcare team. By understanding the symptoms and attending all antenatal appointments, the risks associated with the condition can be managed effectively. Most women with pre-eclampsia go on to have healthy babies, though early delivery (induction) is often recommended to protect the health of both mother and child. 

If you experience a sudden severe headache, changes in your vision, severe pain under your ribs, or sudden swelling of your face or hands, call your maternity unit or 999 immediately. 

Authority Snapshot 

This article has been reviewed by Dr. Stefan Petrov, a UK-trained physician with an MBBS and extensive experience in general medicine and emergency care. It explores the clinical definition, symptoms, and management of pre-eclampsia, adhering to NHS, NICE, and GOV.UK guidelines. Our goal is to provide expectant mothers and their families with clear, evidence-based information to identify this serious pregnancy complication early and ensure the safety of both mother and baby.