Awareness - Frequently Asked Questions
1. What is preeclampsia?
It often occurs in the later stages of pregnancy and is discovered when the blood pressure starts to increase and sometimes when protein in found in the urine test. It 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 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.
2. What's in a name?
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.
3. Is high blood pressure by itself preeclampsia?
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, without these other problems is the milder form of the disease.
4. What increase in blood pressure and when defines preeclampsia?
If your blood pressure was increased before 20 weeks of the pregnancy, it is likely that you have "essential" or chronic hypertension, rather than the blood pressure being a sign of the disease of preeclampsia. Some women have an increase in blood pressure on the oral contraceptive pill and may also experience higher blood pressure in pregnancy without this being a sign of preeclampsia.
5. Am I at risk for preeclampsia?
There is not yet any screening test to tell a woman whether she is at significant risk of developing preeclampsia. A major aim for PEARLS and our colleagues in preeclampsia research worldwide is to develop a simple, effective and affordable screening test.
We can say, though, that there are circumstances that increase the chances of developing preeclampsia, and which make good medical care in pregnancy particularly important:
• 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
• Barrier methods of contraception including condoms - unless there is a period of exposure to the father's proteins before conception, the mother will be less "immunised" to the father's sperm.
Risk is also increased if the mother has a medical condition such as:
• any previous kidney disease, inherited kidney cysts, childhood kidney infections or glomerulonephritis (inflammation of the kidney filters)
6. What do the blood pressure numbers mean?
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 preganncy, 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. The role of the placenta in the control of blood pressure in pregnancy is a major focus of PEARLS and colleagues in preeclampsia research internationally.
7. What risks does preeclampsia present to mother and baby?
However, we are dealing with a very serious disease. One of the most difficult issues when preeclampsia is diagnosed is grappling with the decision that possible early delivery will be required. Pre-eclampsia may require prolonged hospital stay and close specialist observation, to protect against risks of:
• stroke causing temporary or permanent disability
• kidney disease
• fits, seizures, epilepsy
• liver rupture
8. Antenatal care
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 hopsital 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.
• 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.
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 caesarean section will be recommended. Later in pregnancy a vaginal delivery is the optimal form of delivery 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.
11. Care post delivery
12. Future pregnancies
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.
13. Getting answers to more questions
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.
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