All You Need to Know

• What is High Blood Pressure?

  High blood pressure, or hypertension, can occur both in and out of pregnancy. You will not always have symptoms, so it can go unnoticed.

  It is important to be aware of the signs and symptoms of high blood pressure and to have your regular scheduled midwifery checks, as if untreated, high blood pressure in pregnancy can be serious. 

  One in 10 pregnant women have high blood pressure during pregnancy. Of these, some women will already have high blood pressure and some will develop this during pregnancy.

  High blood pressure in pregnancy is defined as having a blood pressure reading of 140/90mmHg (millimetres of mercury) or more. Severe high blood pressure in pregnancy is defined as having a blood pressure reading of 160/110mmHg or higher. 

• Monitoring Your Blood Pressure

  You don’t need normally need to monitor your blood pressure yourself at home, but if you choose to, check that the device you have is suitable for pregnancy:

  Suitable devices

  Sometimes you may be asked to check your blood pressure at home if you have long term high blood pressure. It is important to remember that some monitors are more suitable that others for pregnancy and you should only source a blood pressure monitor that has been advised by your local maternity department.

• Treatment for High Blood Pressure in Pregnancy

  The 3 most frequently used blood pressure reducing (or anti-hypertensive) medications that may be used are:

  Labetalol: This is a medication which is licensed for use in pregnancy to reduce blood pressure. This means the medicine has been used in clinical trials and found to be safe and effective. It works on your heart and blood vessels by blocking small areas called receptors from receiving messages. This reduces your heart rate, and the force which your heart uses to pump blood around your body. It can be taken orally as tablets or given as an injection. Sometimes it can cause your baby to have lower blood sugars at birth, so they will be monitored after birth for this.

  Nifedipine: While nifedipine is not licensed for use in pregnant people, it has been used for many years and is recommended by the National Institute of Clinical Excellence (NICE). Nifedipine works by causing your blood vessels to relax and widen. This reduces your blood pressure. It is taken orally as tablets. There are no known effects on your baby.

  Methyldopa: While methyldopa is not licensed for use in pregnant people, it has been used for many years and is recommended by the National Institute of Clinical Excellence (NICE). Methyldopa works by controlling impulses along nerve pathways. This lowers your blood pressure. It is taken orally as tablets. There are no known effects on your baby.

  All medications can have side effects. The medications listed above can cause headaches, dizziness, feeling tired or weak, or feeling sick. There is not enough research to tell us how often these side effects happen. 
  As each woman/birthing person responds differently to medication, it is important to discuss the treatment options with the medical team and choose an individualised treatment plan that’s right for you.

  Below is a useful decision-making tool to aid discussion around medication use for high blood pressure in pregnancy. 

  High blood pressure in pregnancy - treatment versus no treatment

  High blood pressure in pregnancy - decision aid

  More information about using medicines in pregnancy

• If You Have Existing High Blood Pressure Prior to Pregnancy

  If you have a history of high blood pressure before pregnancy this is known as pre-existing (or chronic) hypertension.

  Of the 10 in 100 pregnant women who have high blood pressure, 2 of these will already have existing high blood pressure. If you have a history of raised blood pressure before pregnancy, you will be referred to a consultant to discuss the risks and benefits of different treatment options and to monitor your pregnancy. Your health care team will work with you to help keep your blood pressure in a healthy range for pregnancy, this is usually around 135/85mmHg.

  There is a potential that you may need adjustments to your medication to help support this and sometimes additional medications alongside your usual ones may be suggested. You might also be advised to take Aspirin (75mg to 150mg) once a day from 12 weeks, but you must check first with your GP or specialist.

  If you are planning a pregnancy, your GP or specialist may refer you to your local maternal medicine team for pre-pregnancy counselling to get specialist advice and support to optimise your health prior to pregnancy.

• What if My Blood Pressure is Found to be High in Pregnancy?

  Sometimes your blood pressure can become high in pregnancy. Of the 10 in 100 women with high blood pressure, 8 of these develop in pregnancy.

  Sometimes this develops without any other symptoms or concerns and is known as pregnancy induced (or gestational) hypertension. Your midwife will check your blood pressure at your booking appointment and antenatal appointments. If your blood pressure is found to be high, it will be arranged for you to be seen at the hospital by the medical team who will plan your care with you. This often involves starting medication to lower the chance of developing severely high blood pressure.

  The choice of medication depends on your medical history and considers the possible side-effects for you and your baby, while also looking to minimise the risk of uncontrolled high blood pressure. As each woman/birthing person responds differently to medication, it is important to discuss the treatment options with the medical team and choose a treatment plan that’s right for you. 

  Your health care team will work with you to help keep your blood pressure in a healthy range for pregnancy, this is usually around 135/85mmHg.

  Our aim is always to work with you to monitor the health and wellbeing of you and your baby throughout pregnancy and look for signs of complication. Women/pregnant people with high blood pressure and their babies are at more risk of complications, including:

  • Developing pre-eclampsia
  • Slowing of the baby’s growth
  • Bleeding behind the placenta (known as a placental abruption)
  • Pre-term birth
  • Admission of the baby into neonatal unit after birth
  • Having a stroke

• What is Pre-Eclampsia?

  Pre-eclampsia is a condition that affects some women/pregnant people, usually from around 20 weeks of pregnancy, or soon after the birth of their baby.

  Pre-eclampsia causes you to have high blood pressure and protein in your urine and can affect your health and the growth and wellbeing of your baby.

  Pre-eclampsia is common - 1 to 5 in 100 women/pregnant people will develop this and it is usually mild, but around 1 in 200 people can develop severe pre-eclampsia, which can be more severe for both mother and baby.

  Pre-eclampsia often has no signs and is first diagnosed at your routine antenatal appointment by your midwife checking your blood pressure and testing your urine. There are some symptoms which can happen either in your pregnancy or after your birth to watch out for:

  • A bad headache that doesn’t go away with simple painkillers
  • Sight problems, such as blurred vision or flashing lights in front of your eyes
  • Severe pain just below your ribs
  • Heartburn that doesn’t go away with antacids
  • Swelling on your face, hands or feet that has suddenly appeared
  • Nausea and vomiting
  • Feeling very unwell

  If you experience one or more of these symptoms, it is important to call your midwifery triage unit immediately.  

• Monitoring For Pre-Eclampsia

  If you have pre-eclampsia in pregnancy, you will need to be monitored carefully. This will be through regular antenatal appointments to check your blood pressure and urine and sometimes some blood tests, as well as ultrasound scans to monitor the growth of your baby.

  Sometimes this can be done with regular visits to the hospital, and sometimes you may need to stay in hospital if your pre-eclampsia is more severe. When you are in hospital, you will have:

  • Regular blood pressure checks to check your blood pressure isn’t going too high
  • Urine tests to check for the protein level in your urine
  • Blood tests to monitor your kidney and liver health
  • Ultrasound scans to check your baby’s growth, the blood flow through the placenta and your amniotic fluid level
  • Checks for any stress in your baby by cardiotocography, or CTG

  You may also be advised to start on medication to reduce your blood pressure. See the treatment for high blood pressure section.

• What Could Happen if Pre-Eclampsia is Not Monitored

  If pre-eclampsia is not diagnosed and monitored, this can progress to severe pre-eclampsia. Sometimes there can be serious complications for both mother and baby, including:

  • Eclampsia, where the woman/pregnant person has fits or convulsions. These are very dangerous, but there is medication you can receive called magnesium sulphate to halve the risk of eclampsia (for information on magnesium, see the treatment for high blood pressure section). Eclampsia is very rare.
  • Blood clotting and liver problems: HELLP syndrome is a blood clotting and liver problem, which can be very dangerous. Disseminated intravascular coagulation (DIC) is another blood clotting problem which can cause bleeding and increase the risk of clots developing in your blood stream. Both are rare, and are treated by delivering the baby as soon as possible and receiving treatment in hospital.
  • Stroke: high blood pressure disturbs blood flow to the brain, which can cause a stroke. This is rare but can be very serious.
  • Organ problems: pre-eclampsia can affect the lungs, liver and kidneys if not diagnosed and monitored.

• Treatment for Pre-Eclampsia

  If you are diagnosed with severe pre-eclampsia, it may be recommended that you start on an infusion or drip of magnesium sulphate. Magnesium sulphate reduces the risk of pre-eclampsia progressing into eclampsia by more than 50%. Eclampsia is where the woman/pregnant person has fits or convulsions. These are very dangerous.

  Magnesium can have some undesirable side effects, including difficulties in breathing, a reduction in urine production which can cause damage to the kidneys, flushing of the skin, sweating, feeling or being sick, headaches, muscle weakness and loss of reflexes like knee jerk and abnormal heartbeat. This can make you feel quite unwell, but a midwife will provide you with one-to-one care and support throughout this and will be monitoring you closely. 

  It is important to treat your blood pressure with medication, often through a drip. See the 'Treatment for high blood pressure in pregnancy' section for more information on the types of treatment.