Causes of Pre-Eclampsia

Pre-eclampsia is a condition affecting women later on in the pregnancy (past the 20 week point), and usually presents subtly with an increase in blood pressure and the presence of protein in urine, and gradually worsens in terms of the symptoms experienced. If left untreated, pre-eclampsia can seriously affect both mother and unborn child. While the symptoms of pre-eclampsia have been well characterised, the causes of the condition remain uncertain. This article discusses what is currently thought to be the main cause of pre-eclampsia, and what that means for the care and prevention of the condition.

Potential causes of pre-eclampsia

It is currently thought that the root of pre-eclampsia lies in the development of the placenta. The placenta is an extremely important organ which forms to provide a medium for the exchange of materials between maternal and foetal blood. A growing foetus needs a regular supply of various nutrients and oxygen, and so an organ designed to ensure that the foetus gets the right amounts of these materials it needs is critical for the health and safety of the foetus. Of equal importance is the placenta’s role in taking away any waste materials generated by the foetus, as these are a natural consequence of bodily functions.

Any defects in the placenta disrupt the important supply of materials to the foetus, but can also affect circulation in the mother, resulting in the characteristic hypertension we see in pregnant mothers suffering from pre-eclampsia. Similarly the waste substances which are usually cleared through the placenta can leak through and pass into mum’s urine, resulting in the characteristic proteinuria we see during pregnancy.

How do problems with the placenta develop?

Placental issues can occur very early on during a pregnancy. One of the first steps after the successful conception stage is the implantation of the newly formed embryo (the name given to the small cluster of cells that is the unborn baby at the very beginning of the pregnancy) into the womb. At this point a special class of cells called villi effectively anchor the embryo to the uterine wall, and work as a primitive placenta. A number of large blood vessels called arteries are responsible for supplying nutrients to the growing embryo through the villi, and during a normal pregnancy these arteries are slowly transformed into larger vessels that are an important part of the placenta. If this transformation doesn’t occur, then the placenta doesn’t function as it should, and it is currently thought that this is a major step in the development of pre-eclampsia.

While placental issues are currently thought to be the main culprit behind pre-eclampsia, the truth is that we aren’t entirely sure what causes the condition. That being said, the understanding of such conditions is always improving, and perhaps more importantly, there are very effective ways of managing the symptoms of pre-eclampsia.

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