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Andy Stein

What causes pre-eclampsia?

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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:
  • Reduced placental blood flow
  • Increased vascular resistance
  • Elevated blood pressure.

2. Endothelial dysfunction 

Endothelial cells line blood vessels, regulating vascular tone. In pre-eclampsia:
  • Endothelial dysfunction impairs vasodilation
  • Increased endothelin-1 levels enhance vasoconstriction
  • Nitric oxide and prostacyclin production decrease.

3. Immunological

Abnormal immune responses contribute to pre-eclampsia:
  • Imbalance between pro-inflammatory and anti-inflammatory cytokines
  • Activation of immune cells (e.g. natural killer cells, macrophages)
  • Increased oxidative stress.

4. Genetic predisposition

Genetic factors influence susceptibility:
  • Family history and twin studies suggest heritability
  • Candidate genes (e.g. STOX1, ACVR2A) implicated
  • Epigenetic modifications also proposed.

5. Environmental and lifestyle factors 

Environmental and lifestyle factors contribute:
  • Low socioeconomic status
  • Obesity
  • Pre-existing medical conditions (e.g. hypertension, diabetes)
  • 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.

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