What is pre-eclampsia?

Pre-eclampsia is a condition which occurs only during pregnancy, affecting 2-8% of pregnancies worldwide¹. It is defined as high blood pressure with leaking of protein from the kidneys into the urine. This makes it a multi-system disorder, which means it affects the heart and blood vessels, the kidneys, the liver and the placenta from functioning effectively. Pre-eclampsia can be mild, moderate or severe depending on the severity of the signs and symptoms, which include headache, fluid retention leading to swollen limbs and face, acute abdominal pain and visual disturbances such as flashing lights or black spots. As a result, mothers who have been diagnosed with pre-eclampsia are classed as ‘high-risk’ and need to be diagnosed and treated in a timely manner. Sadly, the condition not only affects the mother, but also the baby, with risk of growth restriction, preterm birth and stillbirth more likely¹.

What causes it?

The origin of this disorder is the subject of much debate amongst midwives and obstetricians, and if often referred to as the ‘disease of theories’². Only officially recognised as a separate condition from epilepsy in the 18^th century, the current accepted theory is that the condition originates from the placenta during its implantation into the lining of the womb. If the placenta’s blood vessels penetrate the lining of the womb insufficiently, resulting in shallow implantation, this leads to a chain reaction of blood vessel dysfunction throughout the mother, which affects large vessels which control blood pressure, causing it to go up, but also small vessels like capillaries, causing them to leak fluid and cause water retention in the mother’s limbs². What triggers this cascade of events is still unclear, but likely to involve an excessive or atypical maternal immune response. Researchers are still actively working to find out why these immune responses happen and if they can be prevented.

Who is at risk?

In terms of conception, mothers who have conceived using donor eggs are at increased risk of pre-eclampsia as there is a different immune response compared to a conception using her own eggs. The mother’s physical health such as kidney problems, pre-existing high blood pressure and kidney problems, auto-immune disease, polycystic ovaries and diabetes can all increase the risk of pre-eclampsia. Maternal lifestyle choices, such as excessive iron levels, bacterial and viral infections, obesity and mental stress can all increase risk of pre-eclampsia².

Genetics seem to also play a role in risk, with pre-eclampsia running in families. Mothers who were diagnosed with pre-eclampsia are more likely to have daughters who will also suffer from pre-eclampsia. More recently, genetic studies show that it can also be inherited from the paternal line so a family history of both parents is needed to accurately assess risk¹. 

How do I know if I have it?

This condition occurs in the second, but more commonly in the third trimester of pregnancy. Your midwife or doctor will be providing regular check-ups for the signs of pre-eclampsia (such as measuring your blood pressure and checking your urine for protein). You should be aware of the symptoms and monitor these at home, attending your local hospital triage unit if you have any of the following symptoms: severe headache or upper abdominal pain, swelling of arms/legs/face or visual disturbances. It is important to seek care immediately to treat the condition.

What can I do to reduce my risk?
Your midwife or doctor will perform pre-eclampsia screening at your first appointment of the pregnancy and inform you of your risk. If you fall into the high-risk group, you will be advised to take low-dose aspirin between 6-13 weeks. There is good evidence³ to show that in first time mothers, this intervention can reduce your baby being born premature and having a poor outcome. If you are genetically pre-disposed to pre-eclampsia, it may not stop you from developing the condition but it may stop some of the more severe consequences. As Aspirin is not licenced for pregnancy over the counter, you need to obtain a prescription from your healthcare provider. There are some medical conditions in which taking Aspirin is contraindicated, so always discuss with your doctor about your risks.

References:

1. Giannakou K, Evangelou E, Papatheodorou SI. Genetic and non‐genetic risk factors for pre‐eclampsia: umbrella review of systematic reviews and meta‐analyses of observational studies. Ultrasound in Obstetrics & Gynecology. 2018 Jun;51(6):720-30.
2. Jauniaux E, Steer P. Predicting pre-eclampsia: 100 years of trying and failing. BJOG-An International Journal Of Obstetrics And Gynaecology. 2016;123(7):1066.
3. Hoffman MK, Goudar SS, Kodkany BS, Metgud M, Somannavar M, Okitawutshu J, Lokangaka A, Tshefu A, Bose CL, Mwapule A, Mwenechanya M. Low-dose aspirin for the prevention of preterm delivery in nulliparous women with a singleton pregnancy (ASPIRIN): a randomised, double-blind, placebo-controlled trial. The Lancet. 2020 Jan 25;395(10220):285-93.

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