High blood pressure in pregnancy and pre-eclampsia
In brief
Pre-eclampsia is a complication of pregnancy that combines, after 20 weeks, high blood pressure with organ involvement, most often protein in the urine (proteinuria). High blood pressure in pregnancy means a blood pressure of 140/90 mmHg or more on at least two readings; it affects 5 to 10% of pregnancies. A severe headache, problems with your vision or pain under the ribs mean you should go to the maternity emergency department straight away.
What counts as high blood pressure in pregnancy?
High blood pressure (hypertension) in pregnancy is defined as a systolic pressure of 140 mmHg or more and/or a diastolic pressure of 90 mmHg or more, confirmed on at least two readings, at rest. According to the consensus of the French Society of Hypertension and the French College of Gynaecologists and Obstetricians (CNGOF), it affects 5 to 10% of pregnancies. It is one of the situations closely monitored as part of your care for giving birth in Paris and antenatal monitoring.
There are three situations, each with a different outlook:
| Situation | When it appears | Main features |
|---|---|---|
| Chronic hypertension | Before pregnancy or before 20 weeks of pregnancy (weeks of amenorrhoea) | Pre-existing high blood pressure, sometimes discovered in early pregnancy; it continues after the birth |
| Gestational hypertension | After 20 weeks | High blood pressure on its own, without protein in the urine or organ involvement; it usually resolves after the birth |
| Pre-eclampsia | After 20 weeks, mainly in the third trimester | High blood pressure with protein in the urine (at least 0.3 g per 24 hours) or other organ involvement (kidneys, liver, blood, brain, placenta) |
A woman with chronic or gestational hypertension can go on to develop pre-eclampsia. That is why monitoring is not limited to blood pressure readings: doctors also look for signs that organs are affected.
What are the symptoms of pre-eclampsia?
Pre-eclampsia is a disease of the placenta: it does not work properly and releases substances into the mother's bloodstream that damage the blood vessels. It may cause no symptoms and only be picked up by a blood pressure check or a urine test. Some signs, however, should alert you:
- a severe, unusual headache that does not ease with paracetamol;
- problems with your vision: flashing lights, spots, blurred vision;
- buzzing or ringing in the ears;
- a band-like pain just below the breastbone or under the ribs on the right;
- new nausea or vomiting in late pregnancy;
- sudden swelling of the face and hands, rapid weight gain over a few days;
- passing very little urine, or the baby moving less.
Swollen ankles at the end of the day are common and usually harmless. What should alert you is sudden swelling, spreading to the face, or swelling combined with any of the signs above.
What are the risks of high blood pressure in pregnancy for mother and baby?
For the mother
- Eclampsia: a seizure, sometimes preceded by headache and visual problems.
- HELLP syndrome: breakdown of red blood cells, liver involvement and a fall in platelets.
- Placental abruption: sudden separation of the placenta, with pain and bleeding (see our article on bleeding in the second and third trimesters).
- Clotting problems, fluid on the lungs, kidney failure or stroke in severe forms.
For the baby
- Growth restriction, because the placenta delivers less oxygen and fewer nutrients.
- Premature birth, usually decided by the team to protect the mother or baby.
- Less often, acute foetal distress or stillbirth.
Guidelines from the French Society of Anaesthesia and Intensive Care (SFAR) and the CNGOF consider a systolic pressure of at least 160 mmHg or a diastolic pressure of at least 110 mmHg, or any pre-eclampsia with organ involvement, to be severe. These situations require admission to a suitably equipped maternity unit.
How is a pregnancy with high blood pressure monitored?
A pregnancy with high blood pressure is a high-risk pregnancy: care is shared between the obstetrician, the midwife, the GP and, depending on the case, a cardiologist or kidney specialist.
If you had high blood pressure before pregnancy
A consultation before conception is recommended. Some blood pressure medicines must not be taken during pregnancy, including ACE inhibitors and angiotensin II receptor blockers. They must be replaced with pregnancy-compatible treatments, ideally before you conceive or as soon as you have a positive test. Never stop your treatment on your own: talk to your doctor quickly.
During pregnancy
- Home blood pressure monitoring with a validated monitor, as often as the team advises.
- More frequent appointments: their frequency is adapted to your situation and explained at the consultation.
- Testing for protein in the urine (dipstick, then a spot sample or 24-hour collection) and blood tests (platelets, liver enzymes, kidney function).
- Growth scans and Doppler of the uterine and umbilical arteries to check exchanges between the placenta and the baby.
- Foetal heart rate monitoring (CTG) in late pregnancy or if there is any doubt.
Rest and changes to your work are discussed case by case. A balanced diet helps, but a strict salt-free diet is not recommended during pregnancy. Stopping smoking and alcohol is part of the care. These points add to those in routine pregnancy care.
How are high blood pressure and pre-eclampsia treated in pregnancy?
Blood pressure medication protects the mother from severe spikes in blood pressure. It does not cure pre-eclampsia: the only definitive treatment is the birth of the baby and delivery of the placenta.
- Medicines: several drugs can be used during pregnancy (for example methyldopa, labetalol or nicardipine). The choice and dose depend on your situation and are decided during consultation.
- Hospital admission for severe forms, with close monitoring of mother and baby.
- Corticosteroids to speed up the baby's lung maturity when a premature birth is likely.
- Magnesium sulphate in hospital for some severe forms, to prevent eclampsia.
When should the baby be born? The decision weighs the risks to the mother against the risks of prematurity. With well-controlled high blood pressure and no pre-eclampsia, induction may be discussed towards the end of pregnancy. In severe forms, an earlier birth, by induction or caesarean section, may be needed whatever the stage of pregnancy. Maternity units manage these situations according to their level of neonatal care.
When should I go to the maternity emergency department?
Go immediately to the emergency department of the maternity unit where you are booked, or call 15 (SAMU, the French emergency medical service) or 112 in France, or your local emergency number, if you have:
- a severe or unusual headache, or confusion;
- problems with your vision or ringing in the ears;
- severe pain in the upper abdomen or under the ribs;
- a home blood pressure reading of 160/110 mmHg or more, or a sharp rise compared with your usual readings;
- unusual breathlessness or chest pain;
- bleeding, or an abdomen that stays hard and painful;
- fewer movements from the baby, or none;
- a seizure or loss of consciousness (call 15 without delay).
These signs can also appear in the days after the birth. They call for the same response.
What happens after the birth and in a future pregnancy?
Blood pressure continues to be monitored after the birth, as a peak is possible in the first few days. Treatment is adjusted and then gradually reduced. If high blood pressure continues for several weeks after the birth, tests are done to look for chronic hypertension.
- Contraception: contraceptives containing oestrogen are generally not recommended. Progestogen-only methods, the coil (IUD) or the implant are preferred. See our article on contraception.
- Long-term health: a history of high blood pressure in pregnancy or pre-eclampsia increases the risk of high blood pressure and heart disease later in life. Regular checks of blood pressure, weight, cholesterol and blood sugar are recommended.
- Next pregnancy: the risk of recurrence justifies a pre-conception consultation and early follow-up. In high-risk women, low-dose aspirin reduces the risk of preterm pre-eclampsia: in the ASPRE trial, aspirin (150 mg a day) started between 11 and 14 weeks and continued until 36 weeks reduced pre-eclampsia before 37 weeks from 4.3% to 1.6%. Prescription, dose and duration are decided by your doctor.
Frequently asked questions
Are swollen legs in pregnancy a sign of pre-eclampsia?
Usually not: swollen legs at the end of the day are common in pregnancy. However, sudden swelling of the face and hands, rapid weight gain, or swelling with headaches or visual problems mean your blood pressure should be checked without delay.
Can I have a vaginal birth if I have high blood pressure?
Yes, a vaginal birth is often possible, sometimes after induction. A caesarean is kept for situations where the mother's or baby's condition requires a quick birth, or for the usual obstetric reasons.
Can I breastfeed while taking blood pressure medication?
In the vast majority of cases, yes. Several blood pressure medicines are compatible with breastfeeding; your doctor chooses the treatment with your wish to breastfeed in mind.
Does pre-eclampsia go away after the birth?
It usually resolves within days or weeks of the birth, but a temporary worsening is possible in the first few days. Blood pressure must therefore be monitored, then checked again later to detect any persistent high blood pressure.
What blood pressure is normal in pregnancy?
Below 140/90 mmHg. Above this, confirmed on at least two readings at rest, it is called high blood pressure; a reading of 160/110 mmHg or more is a severe form and means you need urgent care.
References
- Mounier-Vehier C, et al. Hypertension and pregnancy. Expert consensus statement from the French Society of Hypertension, an affiliate of the French Society of Cardiology. Presse Med, 2016. doi:10.1016/j.lpm.2016.05.012 — PMID 27402294
- Bonnet MP, et al. Guidelines for the management of women with severe pre-eclampsia. Anaesth Crit Care Pain Med, 2021. doi:10.1016/j.accpm.2021.100901 — PMID 34602381
- Rolnik DL, et al. Aspirin versus Placebo in Pregnancies at High Risk for Preterm Preeclampsia. N Engl J Med, 2017. doi:10.1056/NEJMoa1704559 — PMID 28657417
Dr Olivier KadochObstetrician-gynaecologist and gynaecological surgeon in Paris (16th and 5th arrondissements). Former chef de clinique-assistant (senior registrar) at the Paris public hospitals (AP-HP); individually accredited by the French National Authority for Health (HAS). RPPS 10003957809. Background and practice locations
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