High blood pressure in pregnancy
Types of hypertension in pregnancy
Gestational hypertension—the term used when your blood pressure rises above 140/90 mmHg after 20 weeks of pregnancy, but was normal before this time. It is unattended by any other symptoms. It usually returns to normal soon after the birth of your baby.
Pre-eclampsia refers to a more complex and sever medical condition of pregnancy involving high blood pressure, and usually, protein in the urine. Many women have never had high blood pressure before. This is discussed in greater detail below.
Chronic hypertension—the term used when a woman has high blood pressure before and during their pregnancy. This continues after the birth of the baby.
Treatment for hypertension
Gestational and chronic hypertension can be treated with medication to lower the blood pressure. Several medications have been used safely in pregnancy for many years. Sometimes it is necessary to take more than one type to control a woman's blood pressure.
Not all medications are suitable for use during pregnancy, therefore women with chronic hypertension who are already taking medication may need to change to an alternative treatment during their pregnancy.
Pre-eclampsia affects the health of approximately 1 in 100 pregnant women and their babies. Women who have had pre-eclampsia before, have a family history of pre-eclampsia, are diabetic or have a multiple pregnancy are most at risk. Any pregnant woman, however, can develop pre-eclampsia. Most women feel perfectly well in the early stages of pre-eclampsia and it is not until their condition deteriorates that they experience symptoms.
These symptoms may include:
- persistent headaches
- swelling (oedema) in hands, feet, legs and face
- visual disturbances such as seeing stars or spots, or having blurred vision
- heartburn or pain under your rib cage
- vomiting or feeling generally unwell
- a decrease in your baby's movements.
It is very important that you tell your doctor or midwife if you experience any of these symptoms. Your doctor will look for certain signs when assessing you for pre-eclampsia, including:
- high blood pressure
- protein in your urine
- abnormal blood tests. These test assess how well your liver and kidneys are functioning and how well your blood is clotting, as pre-eclampsia effects these areas in particular.
- brisk reflexes—this is how your joints move when lightly tapped.
The doctor will also assess how your baby is coping. This is often done by:
- monitoring your baby's heart rate pattern over 20 to 40 minutes using a cardiotocograph (CTG) machine
- an ultrasound to assess your baby's growth, how well the placenta is working and how much fluid surrounds your baby.
Admission to hospital
Whether you are admitted to hospital for observation or allowed to rest at home will depend on all the above assessments. Because pre-eclampsia can get worse quickly it is very important that you stay near to a large hospital and notify your doctor or midwife if you experience any of the symptoms mentioned above.
Without treatment pre-eclampsia can, in rare cases, progress to a condition called eclampsia. Eclampsia is life-threatening, and you may have seizures that are similar in appearance to epilepsy. It is described in more detail below.
Treatment of pre-eclampsia
As with gestational and chronic hypertension there are safe medications that can be taken to reduce blood pressure. In the case of pre-eclampsia it may be necessary to administer these medications through an intravenous drip, if your blood pressure is very high.
The only cure for pre-eclampsia is the birth of your baby and placenta. Fortunately, most women who develop pre-eclampsia are more than 36 weeks pregnant. In this case, most women have their labour induced, or undergo a caesarean, and give birth to a healthy, full-term baby.
Unfortunately, some women develop pre-eclampsia before the baby is fully matured. Doctors need to carefully balance the need for your baby to grow and mature—especially their lungs—against how unwell you are. Generally, the best incubator for your baby is your uterus, but pre-eclampsia can restrict the supply of oxygen and nutrients through the placenta, preventing your baby from growing properly.
The doctors may recommend inducing labour early if there are concerns about your health or the growth of your baby. You would usually be given two steroid injections 24 hours apart to prepare your baby's lungs for breathing. If you live a significant distance from a large maternity hospital, you will be transferred prior to delivery to ensure that the neonatal nursery is available to provide advanced care for your preterm baby.
The decision on when to deliver your baby depends on:
- the stage of pregnancy
- how well controlled your blood pressure is
- the results of blood tests that assess your liver and kidney function and blood clotting ability
- how well your baby is growing
- if there are any signs of placental abruption—separation of the placenta from the wall of the uterus.
A decision is made regarding the best time for delivery of your baby after discussion with you, your family and the medical and midwifery staff caring for you. High blood pressure, or hypertension, is one of the most common medical pregnancy complications.
Birth of your baby
An epidural is usually recommended, provided that your blood is clotting properly (epidurals lower blood pressure). Most babies are born vaginally, but on rare occasions the doctor may suggest a caesarean birth.
If doctors are worried that you are in danger of eclampsia, they may recommend magnesium sulphate via an intravenous drip. Magnesium sulphate has long been used to prevent and treat eclampsia. Recent research has shown that it is also effective in preventing eclamptic fits. This is particularly important when transferring a woman from a rural hospital to a large metropolitan hospital for treatment.
Eclampsia is a very rare, but serious, condition that causes maternal convulsions and may lead to stroke, kidney failure or liver failure. It is a medical emergency that may occur if pre-eclampsia is untreated, or does not respond to treatment. Medication that reduces blood pressure and magnesium sulphate to prevent convulsions are given. Unless the mother is close to birth vaginally, the baby is usually delivered by emergency caesarean section as soon as the mother has been stabilised. The mother is then cared for in an intensive care environment until well enough to return to the postnatal ward.
In very rare cases, eclampsia can happen without any previous symptoms and can occur postnatally.
If you develop symptoms of pre-eclampsia or have any concerns please telephone your obstetrician or the birth suite for advice at any time on 07 3163 7444.
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Mater acknowledges consumer consultation in the development of this patient information.
Last modified 18/11/2015.