Preeclampsia is high blood pressure in pregnancy.

It often occurs in the later stages of pregnancy and is discovered when the blood pressure starts to increase and sometimes when protein is found in a urine test. High blood pressure is one of the most common complications of pregnancy, affecting one in ten pregnancies.

The most serious effects occur when blood pressure is dangerously high and the pregnancy needs to be delivered early – ending with a premature baby and a very sick mother.

The mother can suffer headaches, pain under the ribs and often severe swelling. In the worst cases, the high blood pressure can lead to kidney damage, stroke and even death if untreated.

"Eclampsia" was the Latin term for fitting or seizures.

Untreated, high blood pressure in pregnancy can lead to fitting which is why this condition came to be called preeclampsia. In normal pregnancy blood pressure goes down. If you have preeclampsia, blood pressure goes up during the pregnancy.

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In addition to high blood pressure, a diagnosis of preeclampsia involves protein in the urine, liver pain, headache, blood abnormalities or a baby who has stopped growing.

High blood pressure in pregnancy without these other problems is gestational hypertension.

If you are over 20 weeks of your pregnancy then an increase in blood pressure compared to that taken at your first antenatal visit may signal that you are developing preeclampsia. A rise of blood pressure of 25 or more in the first number (the systolic blood pressure) or more than 15 in the second number (the diastolic blood pressure) should be taken seriously.

In Australia the critical markers used are a blood pressure reading of over 140 and/or 90.

If your blood pressure is increased before 20 weeks of your pregnancy you have chronic hypertension. This also puts you at risk of preeclampsia and should be discussed with your health care team.

A number of blood tests have been developed using sFlt1, PlGF or their ratio to one another, which can rule out preeclampsia within 1-4 weeks of testing.

It is extremely important to use the sFlt1/PIGF Ratio Test as an adjunct to clinical assessment by a doctor or health care professional, and not to rely solely on results of the test.

High blood pressure or preeclampsia happens to about 5% of all pregnant women, many in their first pregnancy.

Risk factors include:

• Women at either end of the age range - teenage mothers and women over 35 years
• Assisted reproduction
• Twins or more
• New partner – the risk of preeclampsia is higher for the first pregnancy with a given partner
• Chronic hypertension
• Diabetes
• Lupus
• Any previous kidney disease, inherited kidney cysts, childhood kidney infections or glomerulonephritis (inflammation of the kidney filters).

Blood pressure is defined by 2 numbers: for example, 120 over 80 or 120/80.

The higher number ("systolic blood pressure") reflects the maximum pressure of the blood within the blood vessels (tubing) of the circulation. This maximum burst of pressure occurs with every beat of the heart, when blood is forced by the heart's contraction into the circulation.

The lower number (or diastolic blood pressure) is the pressure measured in between heart beats. This number reflects how full the circulation is.

There is no single normal blood pressure.

Blood pressure measurements taken during a day for any individual person may be very variable. The measurement of blood pressure is affected by the age of the person, whether they are male or female, the level of activity, stress or exercise, sleep, and most importantly, pregnancy.

Common numbers that are recorded when not pregnant are 120/80. When not pregnant, blood pressure is only called high if the readings are taken at rest, repeated several times and go above a set number of 140/90. How this reading is treated will be determined by the age of the person, whether they have other diseases and what medications they may be taking.

In pregnancy, the blood vessels are bathed in all sorts of hormones related to being pregnant. These hormones have the overall effect of lowering the blood pressure by relaxing the blood vessels.

When the circulation is narrowed, or constricted, the blood hits the walls of the blood vessels with increased pressure and the numbers measured are higher. When the blood vessels are relaxed as occurs in normal pregnancy, blood pressure readings are reduced.

Therefore, it is not uncommon to have readings as low as 90/60 early in the pregnancy (often at the first visit to the doctor or midwife at 12 weeks after a missed period). There is no single normal blood pressure in pregnancy. There is a range of numbers that show whether each pregnant woman has responded to the hormones coming from her pregnancy. These numbers are affected by the age of the mother and her usual blood pressure when not pregnant.

The timing of the blood pressure measurement related to the exact number of weeks of the pregnancy is also important. Blood pressure changes between early, middle and late pregnancy. The usual pattern is for both numbers to fall from the first visit to around 24 weeks. It usually stays lower from 24 to 36 weeks and there may be a slight increase blood pressure as the time gets towards delivery. Labour itself does not usually increase blood pressure.

The other unusual feature of blood pressure in pregnancy is that the numbers do not rise as easily in response to activity or stress. This means that the mother keeps her lower pregnant blood pressure even in time of activity and stress that would normally increase blood pressure when not pregnant.

These changes in circulation in pregnancy – lower blood pressure and greater resistance to increases from the body's hormones – seem to be important to keep an adequate amount of blood flowing from the mother's circulation to the placenta which is feeding the baby.

With good medical care the most severe complications of preeclampsia for the mother are rare in Australia, even where a woman has other preexisting medical problems.

Preeclampsia is a very serious condition. One of the most difficult issues when preeclampsia is diagnosed is grappling with the decision that possible early delivery will be required. Preeclampsia may require a prolonged hospital stay and close specialist observation, to protect against risks of:

• accelerated blood pressure
• stroke causing temporary or permanent disability
• bleeding
• kidney disease
• fits, seizures, epilepsy
• liver rupture
• death

At the commencement of pregnancy the earliest health care visit will help to determine your risk of hypertension in pregnancy any prevention strategies. This could include early treatment of high blood pressure and other existing conditions.

Recent research has led to a strong recommendation of initiation of aspirin in women at high risk of developing preeclampsia prior to 16 weeks of gestation.

Also, the use of supplemental calcium is recommended in pregnant women who have a low dietary calcium intake.

Other standard recommendations regarding exercise and vitamins and other supplements should be discussed with your health care team.

The frequency of antenatal visits increases in later pregnancy. This increase is in order to plan for childbirth. Critically the visits assess the growth and development of the baby; but of equal importance, the blood pressure and other screening for preeclampsia.

A number of blood tests have been developed using sFlt1, PlGF or their ratio to one another, which can rule out preeclampsia within 1-4 weeks of testing.

It is extremely important to use the sFlt1/PIGF Ratio Test as an adjunct to clinical assessment by a doctor or health care professional, and not to rely solely on results of the test.

Home blood pressure monitoring can be used in appropriate cases, including where women have chronic or gestational hypertension. The use of home blood pressure monitoring should not replace regular antenatal appointments with your doctor or health care professional.

If the blood pressure is increased at any time before the delivery, then women may be requested to have more frequent blood pressure readings. They might be asked to visit a day stay unit where the blood pressures are taken for a few hours (rather than a one off reading) and the baby is assessed.

If increased blood pressure alone develops, some units may start tablets to lower the blood pressure (or at least prevent further rises in blood pressure). If other features of preeclampsia occur, such as headaches or liver pain, then admission to hospital is likely to be required in a multidisciplinary centre such as a major teaching hospital. It is likely that blood pressure specialists will be involved early in the decision about the use of tablets and the possible timing of the delivery.

Recent research has led to a strong recommendation of initiation of aspirin in women at high risk of developing preeclampsia prior to 16 weeks of gestation.

Also, the use of supplemental calcium is recommended in pregnant women who have a low dietary calcium intake.

Common drugs to treat high blood pressure in use in Australia are:

• Clonidine / Methydopa
• Nifedipine
• Hydralazine
• Diazoxide
• Oxprenolol or Labetolol

These drugs have different mechanisms of action and so often the plan is to use a combination of two at lower doses rather than go for a big dose of one medication. This reduces the side effects of one medication and gains the benefit of lower blood pressure with less side effects.

The medications are generally chosen depending on the experience of the staff using them. There is no scientific evidence to support one medication over another.

Needless to say, newer medications are not proven to be safe in pregnancy by as many years of experience and therefore are not recommended.

Clonidine and Methyldopa have been used for several decades and are commonly used around the globe. They have a "central action" whereby they decrease blood pressure.

Blood pressure elevated during delivery needs to be taken as seriously as in the antenatal period and after delivery. Normal labour does not significantly increase blood pressure.

The reasons for delivery of a baby in preeclampsia relate to the well being of the mother and the baby. If the blood pressure is difficult to control with oral medications or even intravenous medications then delivery to prevent problems from the high blood pressure alone can be required. If the mother is becoming progressively unwell with headache, vomiting or liver pain, then delivery may be recommended. If the blood tests show a deterioration in the platelet count (blood components required to stop bleeding in the delivery), or in the liver or kidney tests, then delivery might be recommended. If the baby is small and or not growing then that is a sign that the placenta is not working properly and that the baby may require early delivery.

The method of delivery depends on the wishes of the mother and her family and carers. The timing of the delivery is also important. If delivery is required earlier than 34 weeks then it is possible that a cesarean section will be recommended. Later in pregnancy a vaginal delivery is often possible depending on the ability of the team to control the blood pressure and also on how well the baby is coping with the delivery process.

Preeclampsia can last as long as 3 months post-delivery. Don't despair, the majority of the symptoms of preeclampsia and the increased blood pressure are gone by the time you are discharged from hospital. If blood pressure continues after delivery then medications can be used that were not necessarily safe when the baby was still in the womb. Fluid tablets can be used if required to help with the fluid problems and high blood pressure of preeclampsia. The blood pressure may need to be checked frequently after delivery until the blood pressure has settled and then the medication can be gradually withdrawn.

Risk of preeclampsia goes down with each pregnancy with the same partner.

If preeclampsia occurs after 34 weeks of gestation then there is a slight risk of it occurring in the next pregnancy.

If the preeclampsia is discovered prior to 34 weeks of gestation, then the chance of there being an underlying blood clotting disorder, renal disease or auto-immune disease are possibly increased. This is more likely in women with a reason for the preeclampsia, kidney disease and prior high blood pressure.

We cannot promise to answer individual questions on line – apart from resource issues, answering any individual woman's questions about her pregnancy properly requires a thorough individual examination and taking a detailed individual history. If you have concerns about your own pregnancy your first contact should be your own doctor, who can arrange referral to a specialist with more detailed knowledge of preeclampsia if necessary

However, if you would like to see questions addressed on this site which you cannot find an answer to at present, please contact us and we will seek to add further material as this site develops.