Preeclampsia: warning signs, thresholds, and when to go to hospital

What is preeclampsia and why does it develop?

Preeclampsia is a condition that develops after week 20 of pregnancy, characterised by new-onset high blood pressure in a woman whose blood pressure was normal before, together with signs of internal organ involvement. The old definition required protein in the urine (proteinuria), but current guidelines recognise that preeclampsia can occur without proteinuria if there is evidence of kidney, liver, platelet, or brain involvement.

The underlying cause is abnormal placental development early in pregnancy. When the spiral arteries of the uterus fail to remodel normally, placental perfusion is reduced, and the placenta releases signals that cause widespread endothelial dysfunction in the mother. The mother's blood vessels constrict and blood pressure rises as a compensatory response. A 2019 review in Circulation Research describes this pathophysiology in detail, emphasising that the disease begins at the placenta weeks before symptoms appear in the mother.

Preeclampsia affects 5% to 10% of pregnancies globally and causes more than 70,000 maternal deaths per year worldwide, the vast majority in low- and middle-income countries. In the Arab world, where access to specialised care is unequal across settings and between countries, preeclampsia and its complications remain a leading cause of maternal mortality.

Who is at highest risk?

High-risk factors for preeclampsia include: a previous pregnancy complicated by preeclampsia (which raises the risk in the next pregnancy to approximately 20-25%), multiple pregnancy (twins, triplets), pre-existing hypertension or kidney disease, pre-existing type 1 or type 2 diabetes, and pregnancy achieved through assisted reproduction. Any one of these high-risk factors alone places a woman in the category that most guidelines recommend for preventive aspirin.

Moderate-risk factors include: first pregnancy (when the maternal immune system is exposed to the paternal antigens in the fetal placenta for the first time), obesity with a body mass index above 35, a family history of preeclampsia in a mother or sister, age above 40, and a gap of more than 10 years between pregnancies. Two or more moderate-risk factors are generally treated as equivalent to one high-risk factor.

The 2019 FIGO initiative introduced a combined first-trimester screening model that integrates risk factors with blood pressure measurement, uterine artery pulsatility index on ultrasound, and maternal serum markers including PAPP-A. This combination identifies approximately 90% of women who will develop preterm preeclampsia, far better than risk-factor questionnaires alone. Not all hospitals in the region offer this full assessment, but identifying high-risk factors is within reach of any antenatal visit.

Warning signs: when does it become an emergency?

The central danger of preeclampsia is that it commonly produces no symptoms in its early stages. Blood pressure is rising, protein is appearing in the urine, and only the antenatal visit detects it. This is why it is unsafe to assume that feeling well means blood pressure is normal. The absence of symptoms is not reassurance.

When symptoms do appear, they signal that the condition has escalated. A severe headache that is unusual for you, particularly felt at the front or back of the head and not relieved by paracetamol, is the most important warning symptom. Visual disturbance including blurring, double vision, or flashing lights or spots means the brain is being affected. Pain in the upper right abdomen, under the ribs, indicates liver involvement and should never be attributed to indigestion or the baby's position without a blood pressure check.

Sudden swelling of the face, hands, or around the eyes is distinct from the gradual ankle swelling common in late pregnancy. Ankle oedema alone is not a sign of preeclampsia, but a rapid onset facial or hand swelling alongside any other symptom warrants same-day assessment. Nausea and vomiting that returns in the third trimester after settling, breathlessness on minimal exertion, and reduced fetal movement are all symptoms that should be reported to your care team immediately.

Blood pressure numbers: what counts as dangerous?

Normal blood pressure in pregnancy is below 130/80 mmHg. In a healthy pregnancy, blood pressure typically falls slightly in the second trimester and returns to pre-pregnancy levels by the third. A reading of 140/90 mmHg or above, confirmed on two occasions at least four hours apart, meets the diagnostic threshold for hypertension in pregnancy. A single reading, even a very high one, is not the whole picture but is enough reason to seek immediate assessment.

The 2021 International Society for the Study of Hypertension in Pregnancy (ISSHP) classification distinguishes between two severity levels. Blood pressure at or above 160/110 mmHg is severe hypertension requiring immediate antihypertensive treatment, because it significantly raises the risk of haemorrhagic stroke in the mother. The range of 140-159 systolic or 90-109 diastolic requires hospital admission for assessment and monitoring, even if the woman feels well.

Home blood pressure measurement provides a valuable safety layer, particularly for women who live far from a hospital or who cannot attend frequent antenatal visits. To get accurate readings: sit quietly for five minutes before measuring, keep the cuff at heart level, do not talk during the measurement, and use an upper-arm cuff of the correct size for your arm circumference. Wrist monitors are less reliable. Take two readings one minute apart and record both.

What blood tests show and what HELLP syndrome means

When preeclampsia is suspected, a standard blood panel checks for organ involvement. A full blood count with attention to the platelet count, liver enzymes (ALT and AST), creatinine and uric acid for kidney function, and urine protein form the core panel. The results determine not just whether preeclampsia is present but how severe it is and which organs are most affected.

HELLP syndrome (Haemolysis, Elevated Liver enzymes, Low Platelet count) is a severe variant of preeclampsia. A platelet count below 100,000 per cubic millimetre combined with rising liver enzymes and hypertension forms the diagnostic triad. HELLP can develop rapidly and can present with atypical features such as nausea, vomiting, and right upper quadrant pain without obvious blood pressure elevation, which makes it easy to miss. It requires delivery regardless of gestational age when severe.

A biomarker ratio called sFlt-1/PlGF is used in some advanced centres to assess the probability that preeclampsia will develop or worsen within the following weeks. It is particularly useful in the borderline zone where blood pressure is elevated but not yet at diagnostic levels. Availability in the region is limited but growing. If your hospital cannot offer it, the clinical assessment of your blood panel, blood pressure trajectory, and symptoms remains the basis of decision-making.

Can preeclampsia be prevented?

Low-dose aspirin is the most effective available prevention for women at high risk. The ASPRE trial, published in the New England Journal of Medicine in 2017, showed that aspirin taken at 150 mg per day from weeks 11 to 16 through to week 36 reduced preterm preeclampsia by more than 62% in women identified as high-risk by first-trimester combined screening. This is one of the most significant findings in obstetric medicine of the past two decades.

Aspirin is recommended only when the risk is genuinely elevated, not as a universal supplement. If you have one or more high-risk factors, or two or more moderate-risk factors, and your doctor has not yet discussed preventive aspirin with you, it is appropriate to ask directly: am I eligible for low-dose aspirin? The prescription cost is minimal and the evidence of benefit at this risk level is strong.

Calcium supplementation reduces blood pressure in pregnant women with low baseline calcium intake, which applies to some women in the region. Vitamins C and E have not been shown to prevent preeclampsia in clinical trials. Complete bed rest is not recommended because it increases the risk of blood clots without preventing preeclampsia. Moderate activity is safe and may help with blood pressure management.

What happens in hospital: treatment and delivery

The only definitive treatment for preeclampsia is delivery, because the placental signals driving the disease stop only when the placenta is removed. The clinical challenge is timing: delivery too early exposes the baby to the complications of prematurity; waiting too long risks deterioration in the mother. Management is therefore a constant balance between monitoring the mother closely and giving the baby additional time for maturity.

Magnesium sulfate given intravenously is the standard prevention for seizures (eclampsia). It is not a blood pressure treatment but a brain protectant. Antihypertensive medications, most commonly labetalol, nifedipine, or methyldopa in this region, are used to bring blood pressure to a safe level. These medications are safe for the baby and do not cross the placenta in amounts that affect fetal function.

In areas where magnesium sulfate is unavailable or where staff training in its administration is limited, the risk to the mother escalates sharply. Eclamptic seizures are survivable with prompt magnesium treatment but highly dangerous without it. If you are in a setting with limited resources and develop severe preeclampsia, transfer to the nearest equipped hospital is the safest course of action, even if it means a long journey.

After delivery: does preeclampsia go away?

In most cases, blood pressure begins to improve within days to two weeks after delivery. However, the first week postpartum is itself a dangerous window. Blood pressure can spike or new-onset seizures can occur in this period even in women who seemed to be improving. Blood pressure monitoring must continue for at least six weeks after delivery, and antihypertensive medication should not be stopped without medical advice.

Women with a history of preeclampsia have a significantly higher lifelong risk of hypertension, cardiovascular disease, and stroke compared with women who were not affected. This does not mean these conditions are inevitable, but it does mean that regular blood pressure, cholesterol, and blood glucose checks are part of appropriate long-term care. Inform any doctor or health professional you see in the future that you had preeclampsia in pregnancy, because it changes what screening is recommended for you.

A subsequent pregnancy should be planned with an early specialist consultation to assess the recurrence risk and determine eligibility for preventive aspirin. Many women who have had preeclampsia go on to have uncomplicated subsequent pregnancies with appropriate monitoring and, where indicated, aspirin from early in the first trimester.

What you can do to stay safe during your pregnancy

Preeclampsia cannot be entirely prevented if risk factors are present, but you can reduce the risk where modification is possible, identify it early, and respond quickly when warning signs appear. Attending every scheduled antenatal visit is the most important single action, because blood pressure and urine protein checks at each visit are the only reliable early detection system.

If you live far from a hospital, a home blood pressure monitor is a meaningful safety investment. Learn the correct technique, keep a dated log of readings, and know the number above which you need to call your doctor on the same day: 140/90 mmHg. Do not wait for additional symptoms before making contact. Elevated blood pressure alone in pregnancy is sufficient reason for same-day assessment.

If you have been diagnosed with preeclampsia and are being managed, follow your care team's instructions about when to come in without waiting to see whether symptoms worsen. Preeclampsia can deteriorate from mild to severe within hours. The time between a warning sign and a decision to come to hospital should be measured in minutes, not days.

Sources

• Mol BWJ, Roberts CT, Thangaratinam S et al: Pre-eclampsia, Lancet (London, England), 2016
• Rana S, Lemoine E, Granger JP et al: Preeclampsia: Pathophysiology, Challenges, and Perspectives, Circulation research, 2019
• Magee LA, Brown MA, Hall DR et al: The 2021 International Society for the Study of Hypertension in Pregnancy classification, diagnosis and management recommendations for international practice, Pregnancy hypertension, 2022
• Rolnik DL, Wright D, Poon LC et al: Aspirin versus Placebo in Pregnancies at High Risk for Preterm Preeclampsia, The New England journal of medicine, 2017
• Duley L: The global impact of pre-eclampsia and eclampsia, Seminars in perinatology, 2009
• Poon LC, Shennan A, Hyett JA et al: The International Federation of Gynecology and Obstetrics (FIGO) initiative on pre-eclampsia: A pragmatic guide for first-trimester screening and prevention, International journal of gynaecology and obstetrics, 2019