Pre-eclampsia is the most common of the serious complications arising in pregnancy, which can affect the mother, her unborn child, or most commonly, both.

What happens to the mother?

Signals from the deficient placenta affect the mother’s blood vessels, raising her blood pressure and disturbing her kidney function, so that waste products which should be excreted in the urine accumulate in the blood, while valuable blood proteins leak into the urine.

As the disease progresses, the mother’s liver, lungs, brain and blood clotting system can also be affected. Eclampsia (convulsions), cerebral haemorrhage (stroke), pulmonary oedema (fluid in the lungs), kidney failure, liver damage, and breakdown of the blood clotting system (disseminated intravascular coagulation) are the most dangerous complications – all of them fortunately, very rare.

What happens to the baby?

As the blood supply from the mother to the placenta is restricted, the baby’s supply of nutrients and oxygen may be reduced, leading at first to slower than normal growth (intrauterine growth retardation – IUGR) and later to oxygen starvation.

Once pre-eclampsia is suspected or known, the unborn baby is monitored as closely as the mother so that the delivery can be carried out before its problems become serious. Decisions about early induction are particularly difficult when a premature foetus (of under 28-30 weeks’ gestation) is severely affected by pre-eclampsia but could not be certain of survival outside the womb.

What treatments are used?

Mothers are admitted to hospital if they have pre-eclampsia, which means protein in the urine as well as high blood pressure. This is to enable doctors and midwives to monitor the progress of mother and baby as closely as possible so that a safe induction, if necessary carried out before complications set in.

Pre-eclampsia is progressive – it doesn’t get better and usually gets worse. So, once admitted, mothers are not normally allowed home until after their baby has been born. Antihypertensive drugs, which reduce high blood pressure, are often prescribed; although they do not affect the underlying disease, they can reduce the risk of some complications, such as cerebral haemorrhage. Anticonvulsant drugs may also be prescribed to ward off eclamptic fits.