Pregnancy—high blood pressure

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 does not produce any other symptoms and usually returns to normal soon after the birth of your baby.

Pre-eclampsia—refers to a more complex and severe medical condition of pregnancy involving high blood pressure and usually protein in the urine. You may never have had high blood pressure at all before this pregnancy. This is discussed in greater detail below.

Chronic hypertension—the term used when you have high blood pressure before and during your pregnancy. This continues after the birth of your baby.

Treatment for hypertension

Gestational and chronic hypertension can be treated with medication to lower your blood pressure, although this is not always required. Several medications have been used safely in pregnancy for many years; sometimes it is necessary to take more than one type of medication to control your blood pressure.

Not all medications are suitable for use during pregnancy; therefore, if you have chronic hypertension and are already taking medication, you may need to change to an alternative treatment during your pregnancy.

Pre-eclampsia

Pre-eclampsia affects the health of approximately 1 in 100 pregnant women and their babies. If you have had pre-eclampsia before, have a family history of pre-eclampsia, are diabetic or have a multiple pregnancy, you are more at risk of developing pre-eclampsia with this pregnancy. However, any pregnant woman can develop pre-eclampsia.

You may feel perfectly well in the early stages of pre-eclampsia and it is not until your condition deteriorates that you may experience any symptoms.

These symptoms may include:

• persistent headaches
• oedema (swelling) in your 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—pre-eclampsia effects these areas in particular
• brisk (quick) reflexes—this is how your joints (e.g. elbows or knees) move when lightly tapped.

The doctor will also assess how your baby is coping by:

• monitoring your baby's heart rate pattern for 20 to 40 minutes (or longer, if necessary) 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.

Treatment of pre-eclampsia

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.

Medication—as with gestational and chronic hypertension there are safe medications that can be taken to reduce blood pressure, although this is not always required. 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.

Stopping pre-eclampsia—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, so either have their labour induced, or undergo a caesarean, giving birth to a healthy, full-term baby.

Unfortunately, some women develop pre-eclampsia before their 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.

Your doctor may recommend inducing labour early if there are concerns about your health or your baby's growth. 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 away 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.

A decision will be made regarding the best time to deliver your baby after discussion with you, your family and the medical and midwifery staff caring for you. This decision depends on:

• the stage of your 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.

An epidural is often recommended during labour, provided that your blood is clotting properly as epidural anaesthesia can lower blood pressure. Most babies are born vaginally, but on rare occasions your doctor may suggest a caesarean birth.

Preventing eclampsia

If your doctors are worried that you are in danger of eclampsia, they may recommend treatment with magnesium sulphate via an intravenous drip. Magnesium sulphate has been used for many years to prevent and treat eclampsia. Recent research indicates that it is also effective in preventing eclamptic fits. This is particularly important when transferring a pre-eclamptic/eclamptic woman from a rural hospital to a large metropolitan hospital for treatment.

Eclampsia

Eclampsia is a very rare, but serious, condition that causes maternal convulsions (seizures) 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 to reduce blood pressure and magnesium sulfate to prevent convulsions are given. Unless you are close to birthing vaginally, your baby will usually be delivered by emergency caesarean section as soon as you have been stabilised. You will then be cared for in an intensive care environment until you are well enough to be transferred to the postnatal ward.

In very rare cases, eclampsia can happen without any previous symptoms and can also occur after the birth of your baby.

Your doctor or midwife has asked you to monitor your blood pressure (BP) at home. This information will give you instructions on how to do this and what to do with your BP reading.

Why is checking my BP important? 

A BP measurement is recommended at every pregnancy care visit because high blood pressure (hypertension) is common in pregnancy. 

Having regular BP measurements is a part of keeping you and your baby safe, through ensuring your BP remains normal and you are not developing high blood pressure, or pre-eclampsia.

How do I check my BP at home?

• Sit comfortably at rest and place your feet flat on the floor. 
• Make sure you are using the right size BP cuff (the part that wraps around your arm).
• Sit upright and rest for 2 minutes before taking your BP. 
• Do not take your blood pressure when you are feeling stressed or in pain, as it will likely be higher. 

Checking your BP for your telehealth appointment?

Only take your blood pressure during your Telehealth appointment unless otherwise advised.
If you are unsure about how to do this, your doctor or midwife can assist you during your Telehealth appointment.

Alternatively, you could ask your GP to measure your BP and write this down for you or you can take a photo of the measurement. This is best done the day of your telehealth appointment.
Your doctor or midwife will discuss your blood pressure result with you during your Telehealth appointment.  
If your BP measurement is 140/90 (or higher) we will ask you to come to the Pregnancy Assessment Centre (PAC) for further assessment. 

Women diagnosed with high BP

1. If your BP is less than or equal to 140 systolic (top number) and/or less than or equal to 90 diastolic (bottom number) it is normal. Keep a record of your readings to show the midwife or doctor at your next routine review.
2. If your BP is greater than or equal to 160 systolic and/or 110 diastolic it is high and you need to come to PAC.
3. If your BP is between 140–160 systolic and /or 90–110 diastolic—you need to rest for 15 minutes and then repeat the reading (sitting upright).  If it remains between 140–160/90–110 we recommend you attend PAC for review within 4 hours.

When else should I come to hospital?

If you have new symptoms that are concerning you, we recommend you attend PAC for review – even if your BP readings are normal.

BP machine—buy or hire

BP machines can be bought or hired through many local pharmacies. You may be able to claim some costs through your private health insurance.

Be sure to check with the pharmacist that you have the correct sized arm cuff and that the machine is appropriate for use in pregnancy.

If you develop symptoms of pre-eclampsia or have any concerns, at any time, please telephone your obstetrician, or Mater's Pregnancy Assessment Centre on 07 3163 7000.