What causes pre-eclampsia?
Pre-eclampsia is a complication of pregnancy characterised by high blood pressure, protein in the urine and potential damage to organs such as the liver, kidneys and brain.
It is common(ish) and affects approximately 5% of pregnancies. Despite extensive research, the exact cause of pre-eclampsia remains unclear.
At worst it can worsen and become eclampsia and is life-threatening. Fortunately, most cases are milder and resolve when the baby is delivered.
This article summarises some of the prevailing theories for what causes pre-eclampsia.
1. Placental hypoperfusion
The placenta plays a crucial role in pre-eclampsia development. Inadequate trophoblast invasion and defective placental vascular remodelling lead to:
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Reduced placental blood flow
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Increased vascular resistance
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Elevated blood pressure.
2. Endothelial dysfunction
Endothelial cells line blood vessels, regulating vascular tone. In pre-eclampsia:
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Endothelial dysfunction impairs vasodilation
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Increased endothelin-1 levels enhance vasoconstriction
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Nitric oxide and prostacyclin production decrease.
3. Immunological
Abnormal immune responses contribute to pre-eclampsia:
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Imbalance between pro-inflammatory and anti-inflammatory cytokines
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Activation of immune cells (e.g. natural killer cells, macrophages)
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Increased oxidative stress.
4. Genetic predisposition
Genetic factors influence susceptibility:
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Family history and twin studies suggest heritability
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Candidate genes (e.g. STOX1, ACVR2A) implicated
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Epigenetic modifications also proposed.
5. Environmental and lifestyle factors
Environmental and lifestyle factors contribute:
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Low socioeconomic status
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Obesity
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Pre-existing medical conditions (e.g. hypertension, diabetes)
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Multiple pregnancy.
Summary
We have described what causes pre-eclampsia – i.e. the precise cause in unknown. Theories are listed above. It is probably due to a combination of the above. We hope this has been helpful.
