--- title: 'Understanding The Early Warning Signs of Pre-eclampsia' slug: pre-eclampsia-warning-signs-pregnancy lifeStage: pregnancy category: Symptoms medicalReviewer: 'Dr Shree Datta, Consultant Obstetrician and Gynaecologist ' reviewerId: 'https://blog.bloume.com/pregnancy/medical-board.md#dr-shree-datta' lastUpdated: '2026-07-21' primarySource: 'Pre-eclampsia Patient Information' --- # Understanding The Early Warning Signs of Pre-eclampsia Pre-eclampsia can develop from 20 weeks of pregnancy, bringing together high blood pressure and protein in your urine. In its early stages it often causes no symptoms you would notice, which is why routine antenatal checks matter so much. As it progresses, certain warning signs need urgent medical attention. This article explains what pre-eclampsia is, what to look out for, and when to get help without delay. **Q: From what point in pregnancy can pre-eclampsia develop?** A: Pre-eclampsia usually develops after 20 weeks of pregnancy. In some cases it can appear shortly after birth. It does not happen in the first half of pregnancy. You can feel completely well while pre-eclampsia is quietly developing, which is part of why its warning signs are so easy to miss in pregnancy. In the early stages it often brings no symptoms you would notice, even as your blood pressure starts to rise. That is why the blood pressure cuff and urine dipstick at each antenatal appointment are how pre-eclampsia is most often picked up. Pre-eclampsia develops after 20 weeks of pregnancy, or sometimes shortly after birth, and shows up as a mix of high blood pressure and protein in your urine. ## What is pre-eclampsia? Pre-eclampsia is two things happening at once: high blood pressure (hypertension) and protein in your urine (proteinuria). The exact cause is not fully understood, though it seems to come down to how the placenta develops. When the placenta does not develop as it should, blood flow to it can drop. That affects your baby's growth and can set off a response in your body that raises blood pressure and puts strain on several organs. Pre-eclampsia affects up to 8 in 100 pregnancies in the UK, and many cases are mild. Severe pre-eclampsia is less common and develops in a small number of pregnancies. ## Blood pressure and what the numbers mean High blood pressure is the main thing your midwife or doctor is checking for. A reading of 140/90 mmHg or higher, taken on two separate occasions at least four hours apart, is generally counted as high in pregnancy. One high reading on its own is not enough to confirm anything; the two-occasion rule is there to tell a genuine, lasting rise apart from a one-off. This is the threshold your care team uses, not a number you need to apply to a home monitor yourself. The other main sign is protein in the urine, which indicates the kidneys may be affected. This is why urine is checked at every antenatal appointment. If the dipstick shows anything worth investigating, your midwife or care team will arrange further testing to get a clearer picture. ## Pre-eclampsia warning signs to know Because early pre-eclampsia brings no symptoms you would feel, there is no way to pick it up at home before it progresses. As it advances, certain symptoms can appear. If you notice any of the following, get medical help straight away and do not wait for your next appointment. - A severe headache that ordinary painkillers do not ease - Problems with your vision, like blurring or flashing lights - Severe pain just below your ribs - Heartburn that does not ease with antacids - Sudden swelling of your face, hands, or feet (different from the gradual ankle swelling that is common in pregnancy) - Feeling very unwell in yourself Heartburn and swollen feet are common in pregnancy and on their own do not point to pre-eclampsia. What matters is sudden onset, how severe it feels, or several of these signs showing up together. If you are unsure, call your midwife or maternity unit. > **WARNING**: If you have a severe headache, problems with your vision, severe pain below your ribs, or sudden swelling, get medical help straight away. Call your midwife, GP surgery, or your local hospital's maternity unit. Do not wait for your next appointment. In an emergency, call 999. ## Why antenatal appointments are the first line of detection Because pre-eclampsia can develop without any symptoms you would notice, getting to all your scheduled antenatal appointments matters. Each one includes a blood pressure check and a urine test, there to catch changes before they become serious. These checks are how it is most often spotted at an early, more manageable stage. Appointments matter, and so does paying attention to how you feel between them. The symptoms above can appear at any time. If they do, contact your midwife or maternity unit that day rather than waiting for your next appointment. --- **Q: From what point in pregnancy can pre-eclampsia develop?** Pre-eclampsia usually develops after 20 weeks of pregnancy. In some cases it can appear shortly after birth. It does not happen in the first half of pregnancy. **Q: What blood pressure reading is considered high in pregnancy?** A reading of 140/90 mmHg or higher, taken on two separate occasions at least four hours apart, is generally counted as high in pregnancy. One reading above this on its own is not enough. Your midwife or doctor will assess it as part of your antenatal care. **Q: Can you have pre-eclampsia without any symptoms?** Yes. In its early stages, pre-eclampsia often brings no symptoms you would notice. High blood pressure and protein in your urine, both picked up through routine antenatal checks, are usually the first signs. This is why getting to all your scheduled appointments matters even when you feel well. **Q: Which symptoms mean you should seek help straight away?** Call your midwife, GP surgery, or maternity unit straight away if you develop a severe headache that ordinary painkillers do not ease, problems with your vision such as blurring or flashing lights, severe pain just below your ribs, or sudden swelling of your face, hands, or feet. Do not wait for your next appointment. In an emergency, call 999. **Q: What is the purpose of the urine test at antenatal appointments?** Your urine is checked with a dipstick at every antenatal appointment to look for protein, which can be a sign your kidneys are being affected by pre-eclampsia. If the dipstick shows a certain level of protein, your care team may arrange a more detailed test to measure the amount more precisely. ### Clinical Sources - [Pre-eclampsia Patient Information](https://www.rcog.org.uk/for-the-public/browse-our-patient-information/pre-eclampsia/) - [Pre-eclampsia Patient Information](https://www.rcog.org.uk/for-the-public/browse-our-patient-information/pre-eclampsia/) - [Pre-eclampsia Patient Information](https://www.rcog.org.uk/for-the-public/browse-our-patient-information/pre-eclampsia/) - [Pre-eclampsia](https://teachmeobgyn.com/pregnancy/hypertensive-disorders/pre-eclampsia/) - [The 2019 NICE Guideline on Hypertension in Pregnancy](https://action-on-pre-eclampsia.org.uk/wp-content/uploads/2020/02/NICE-Guideline-Talk-FCR-2020_02_04.pdf) - [Pre-eclampsia - Patient Information](https://www.uhs.nhs.uk/Media/UHS-website-2019/Patientinformation/Pregnancyandbirth/Pre-eclampsia-4046-PIL.pdf) - [Pre-eclampsia - Patient Information](https://www.uhs.nhs.uk/Media/UHS-website-2019/Patientinformation/Pregnancyandbirth/Pre-eclampsia-4046-PIL.pdf) - [Pre-eclampsia Patient Information](https://www.rcog.org.uk/for-the-public/browse-our-patient-information/pre-eclampsia/) --- Reviewed by Dr Shree Datta, Consultant Obstetrician and Gynaecologist | [Medical Board](https://blog.bloume.com/pregnancy/medical-board.md) | July 2026