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High blood pressure in pregnancy

Types of hypertension in pregnancy

Gestational hypertension is 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.

Chronic hypertension is the term used when someone has high blood pressure before and during their pregnancy. This continues after the birth of the baby.

Pre-eclampsia refers to a more complex and sever medical condition involving high blood pressure and protein in the urine. Many women have never had high blood pressure before. This is discussed in greater detail below.

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.

That being said, not all medications are suitable for use during pregnancy. Women with chronic hypertension who are already taking medication may need to change during their pregnancy.

Pre-eclampsia

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 they are quite ill 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
  • decrease in your baby's movements.

It is very important that you tell your doctor or midwife if you experience these symptoms. You 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 20–40 minutes using a CTG (cardiotocograph) machine
  • ultrasound to look at your baby's growth, how well the placenta is working and how much fluid is around the baby.

Admission to hospital

Whether you are admitted to hospital for observation or go 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 any of your symptoms become worse.

If pre-eclampsia is allowed to get worse without treatment it can lead, in rare cases, to a condition called eclampsia. Eclampsia is life-threatening, involving fits similar in appearance to epilepsy. It is described in more detail below.

Treatment of pre-eclampsia

Medication for hypertension

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 the blood pressure is very high.

Preventing Eclampsia

If doctors are worried that a woman is in danger of eclampsia, they may decide to give her magnesium sulphate via an intravenous drip. Magnesium sulphate has long been used to 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.

Stopping Pre-eclampsia

The only cure for pre-eclampsia is delivery of the 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 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 the baby to grow and mature—especially their lungs—against how sick the mother is. Generally, the best incubator for a baby is their mother's uterus, but pre-eclampsia can restrict the supply of oxygen and nutrients through the placenta, preventing the baby from growing properly.

The doctors may decide to induce the labour early if they are worried about the mother's health or the growth of the baby. The mother is usually given two steriod injections 24 hours apart to prepare the baby's lungs for breathing. If the mother lives far away from a large maternity hospital, she will be transferred prior to delivery to ensure that the neonatal nursery is available to provide advanced care for the premature baby.

When to deliver the baby depends on:

  • the stage of pregnancy
  • how well controlled the mother's blood pressure is
  • the results of blood tests that assess liver and kidney function and blood clotting ability
  • how well the baby is growing
  • if there are any signs of placental abruption (separation of the placenta from the wall of the womb).

A decision is made regarding the best time for delivery after discussion with the woman, her family and the medical and midwifery staff caring for her. High blood pressure, or hypertension, is one of the most common medical pregnancy complications.

Birth of the baby

An epidural is usually recommended, provided that the woman's blood is clotting properly (epidurals lower a woman's blood pressure). Most babies are born vaginally, but on rare occasions the doctor may suggest a caesarian section.

Eclampsia

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 left untreated, or does not respond to vigorous treatment. Medication that reduces blood pressure and magnesium sulphate is usually given through an intravenous drip. 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.

Further information and support

Talk to your doctor and midwife and try some of these websites:
The pre-eclampsia site www.pre-eclampsia.co.uk
The Cochrane database www.cochrane.org
Pre-eclampsia Foundation www.preeclampsia.org

If you develop symptoms of pre-eclampsia or have any concerns please phone the Birth Suite for advice at any time on 07 3163 1918.