High blood pressure is one of the more common problems in pregnancy, and one of the most important to catch early. The good news is that with regular antenatal checks it is usually picked up and managed well before it causes harm.

Warning signs — when to contact us straight away

Many women with raised blood pressure feel completely well, which is exactly why we check it at every visit. But if you develop any of the following, contact us or attend hospital without waiting for your next appointment:

  • A severe headache that does not settle
  • Vision problems — blurring, flashing lights, or sensitivity to light
  • Pain below the ribs, usually on the right side
  • Sudden swelling of the face, hands or feet
  • Vomiting in later pregnancy
  • Noticeably reduced baby movements

These can be signs of pre-eclampsia, which needs prompt assessment.

The three types of high blood pressure in pregnancy

  • Chronic hypertension — blood pressure that was already high before pregnancy, or that appears before 20 weeks.
  • Gestational hypertension — blood pressure that rises after 20 weeks, with no protein in the urine.
  • Pre-eclampsia — raised blood pressure after 20 weeks together with protein in the urine or signs that other organs are affected. This is the most serious form.

Who is more likely to develop it

  • A first pregnancy
  • A previous pregnancy with pre-eclampsia, or a family history of it
  • Existing high blood pressure, diabetes or kidney disease
  • A high body mass index
  • Being over 35
  • Carrying twins or more
  • A gap of ten years or more since your last pregnancy

When we start treatment

Not every raised reading needs medication straight away. What we do depends on your blood pressure, your symptoms and your test results.

  • If you have symptoms, we treat at a blood pressure of 140/90 — that is, the top number reaching 140 or the bottom number reaching 90.
  • If you have no symptoms, your investigations are normal and there is no protein in your urine, we usually observe you for about 24 hours first and then decide whether medication is needed. This is normally done as an inward stay, though some women are monitored by their general practitioner instead. Blood pressure often settles with rest and repeat measurement, and this avoids treating a single high reading unnecessarily.

The medicines we use

Three medicines are used in pregnancy, and all three are safe and effective. We use them interchangeably, choosing according to your circumstances:

  • Nifedipine — commonly the first choice, because of its side-effect profile.
  • Methyldopa — preferred by some clinicians and a well-established option.
  • Labetalol — generally used as a second-line medicine.

Your doctor will explain which one you are on and why. Never stop or change a blood pressure medicine in pregnancy without speaking to us first.

Monitoring you and your baby

If your blood pressure is raised, we will see you more often. Monitoring usually includes regular blood pressure checks, urine testing for protein, blood tests for your kidneys, liver and platelets, and scans to check your baby’s growth and wellbeing. Where pre-eclampsia is confirmed or blood pressure is difficult to control, the safest course is sometimes to plan an earlier birth — your doctor will discuss the timing and method with you.

Can it be prevented?

Not entirely, but risk can be reduced. Keeping to a healthy weight, eating well, staying active, avoiding smoking and alcohol, and managing any existing diabetes or high blood pressure all help. Good calcium intake also lowers the risk of pre-eclampsia — see our guide to calcium in pregnancy.

Low-dose aspirin lowers the risk of pre-eclampsia in women who are at high risk, but it is prescribed by your doctor for selected women — it is not something to start on your own.

Above all, attend your antenatal appointments. Blood pressure is checked at every visit precisely because the problem is usually silent in its early stages.

The bottom line

High blood pressure in pregnancy is common, manageable and usually silent early on. We treat at 140/90 if you have symptoms; if you feel well and your tests are normal, we observe you for around a day — usually as an inward stay — before deciding. Nifedipine, methyldopa and labetalol are all safe choices. Keep your appointments, and contact us straight away about a severe headache, visual disturbance, upper abdominal pain or reduced baby movements.

References

  1. National Institute for Health and Care Excellence. Hypertension in pregnancy: diagnosis and management. NG133. London: NICE; 2019. Available from: https://www.nice.org.uk/guidance/ng133
  2. National Health Service. Pre-eclampsia [Internet]. NHS; [cited 2026 Jul 22]. Available from: https://www.nhs.uk/conditions/pre-eclampsia/
  3. Brown MA, Magee LA, Kenny LC, et al. The hypertensive disorders of pregnancy: ISSHP classification, diagnosis and management recommendations for international practice. BJOG. 2018;125(7):803–816.
  4. World Health Organization. WHO recommendation: calcium supplementation during pregnancy for the prevention of pre-eclampsia and its complications. Geneva: WHO; 2018. Available from: https://www.who.int/publications/i/item/9789241550451