# Preeclampsia in plain language: what it is, who is at risk, and what to watch for

> Preeclampsia affects roughly 3 to 4 percent of pregnancies in Australia. Here is what the diagnostic criteria actually mean, which risk factors matter, which symptoms to take seriously, and what the evidence says about aspirin prevention and long-term health.

URL: https://trymycocoon.com/blog/preeclampsia-in-plain-language/
Category: Pregnancy in plain language
Last updated: 2026-08-05

> **This article is for general information only, not medical advice.** It has not been reviewed by a clinician. If you have symptoms you think might be preeclampsia, contact your midwife or maternity unit today. For severe symptoms including persistent headache not relieved by paracetamol, visual disturbances, sudden face or hand swelling, or very high blood pressure, call emergency services or go to your nearest emergency department immediately. No app tool replaces clinical assessment.

## What is preeclampsia, and when does it happen?

Preeclampsia is a pregnancy complication involving new-onset high blood pressure, defined as a systolic reading of 140 mmHg or higher or a diastolic of 90 mmHg or higher, confirmed on two occasions at least four hours apart, developing after 20 weeks of pregnancy. The modern diagnostic criteria, adopted by both SOMANZ and ACOG, do not require protein in the urine: preeclampsia can also be diagnosed when there are signs of organ involvement, including a platelet count below 100,000 per microlitre, impaired kidney or liver function, pulmonary oedema, or new-onset severe headache or visual symptoms. Preeclampsia affects roughly 3 to 4 percent of pregnancies in Australia and New Zealand, and between 2 and 8 percent globally. ([RANZCOG consumer resource, High Blood Pressure and Preeclampsia During Pregnancy, 2023](https://ranzcog.edu.au/wp-content/uploads/HBP-Preeclampsia-During-Pregnancy.pdf); [Incidence of preeclampsia and eclampsia in Australia 2000-2008, PubMed PMID 23467048](https://pubmed.ncbi.nlm.nih.gov/23467048/))

The 20-week threshold matters clinically. High blood pressure before 20 weeks is classified as chronic hypertension, a different condition managed differently. After 20 weeks, new hypertension that resolves within 12 weeks after birth is called gestational hypertension. Preeclampsia is the diagnosis when the full criteria are met. Most cases are detected in the third trimester, but the condition can appear earlier, particularly in high-risk pregnancies.

The SOMANZ Hypertension in Pregnancy Guideline, co-published with RANZCOG in 2023 and based on the ISSHP 2018 classification framework, is the primary Australian and New Zealand clinical guide for this condition. It uses the same diagnostic thresholds and aligns with ACOG Practice Bulletin 222, the benchmark US document. ([SOMANZ Hypertension in Pregnancy Guideline 2023](https://ranzcog.edu.au/wp-content/uploads/SOMANZ-Hypertensive-Disorders-Pregnancy.pdf); [Practice Bulletin 222, Gestational Hypertension and Preeclampsia, ACOG, 2020](https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2020/06/gestational-hypertension-and-preeclampsia))

*Last reviewed: 5 August 2026.*

## Who is at higher risk of preeclampsia?

ACOG's Practice Bulletin 222, and the SOMANZ guideline that aligns with it, divide preeclampsia risk into two tiers. High-risk factors, where a single factor is enough to recommend preventive aspirin, include: a previous pregnancy complicated by preeclampsia (the strongest single risk factor, with a relative risk of 8.4 in meta-analysis), carrying more than one baby, chronic hypertension, type 1 or type 2 diabetes, and kidney disease. Antiphospholipid antibody syndrome and systemic lupus erythematosus are also in the high-risk group. ([Clinical risk factors for pre-eclampsia determined in early pregnancy: systematic review and meta-analysis of large cohort studies, PMC, 2016, PMC4837230](https://pmc.ncbi.nlm.nih.gov/articles/PMC4837230/); [Practice Bulletin 222, ACOG, 2020](https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2020/06/gestational-hypertension-and-preeclampsia))

Moderate-risk factors, where two or more together reach the threshold, include: first pregnancy (nulliparity, relative risk 2.1), a BMI above 30, a family history of preeclampsia in a mother or sister, age 35 or older, low socioeconomic status, and in vitro fertilisation conception. The additive model matters here. A first pregnancy alone is not an isolated high-risk signal. A first pregnancy at 37, with a BMI of 32, a mother who had preeclampsia, and an IVF conception, is a different picture entirely.

**Aspirin prevention.** For women with one high-risk factor, or two or more moderate-risk factors, low-dose aspirin reduces the risk of preterm preeclampsia. The ASPRE trial, a multicentre double-blind RCT published in the New England Journal of Medicine in 2017, randomised high-risk women to 150 mg aspirin per day or placebo starting at 11 to 14 weeks. Preterm preeclampsia occurred in 1.6 percent of the aspirin group and 4.3 percent of the placebo group, an odds ratio of 0.38 and a 62 percent relative reduction. ([Rolnik DL et al., Aspirin versus Placebo in Pregnancies at High Risk for Preterm Preeclampsia, NEJM, 2017, PMID 29236633](https://pubmed.ncbi.nlm.nih.gov/29236633/)) RANZCOG and SOMANZ recommend 100 to 150 mg per day, taken at bedtime, starting at 11 to 14 weeks. ACOG and the USPSTF recommend 81 mg per day from 12 to 28 weeks gestation, with strongest evidence for starting before 16 weeks. ([USPSTF Final Recommendation, Aspirin Use to Prevent Preeclampsia, 2021](https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/low-dose-aspirin-use-for-the-prevention-of-morbidity-and-mortality-from-preeclampsia-preventive-medication); [RANZCOG C-Obs 61, Screening and Prevention of Preterm Preeclampsia, PDF](https://ranzcog.edu.au/wp-content/uploads/Screening-Prevention-Preterm-PET.pdf)) If any risk factors apply, raise aspirin at your first antenatal appointment.

No other intervention has equivalent evidence. Bed rest, salt restriction, vitamin C and E supplements, and dietary calcium are not recommended as preventive measures for preeclampsia.

## What symptoms are worth taking seriously?

The difficulty with preeclampsia is that early cases often produce no noticeable symptoms at all. Blood pressure does not cause pain. This is the main reason antenatal appointments exist. Regular checks detect a condition you would not otherwise know you had. Attending every scheduled appointment, including when you feel well, is one of the most effective things you can do.

Symptoms that warrant same-day contact with your midwife or maternity unit include: a persistent headache not relieved by paracetamol; visual disturbances such as blurred vision, seeing spots or flashing lights, or light sensitivity; sudden severe swelling of the face or hands (distinct from the gradual ankle swelling that is common in late pregnancy); and pain in the upper abdomen, particularly under the right ribs. These can indicate severe preeclampsia or HELLP syndrome and can escalate quickly. ([NHS, Pre-eclampsia](https://www.nhs.uk/conditions/pre-eclampsia/); [NICE NG133, Hypertension in Pregnancy: Diagnosis and Management, 2019 updated 2023](https://www.nice.org.uk/guidance/ng133))

Do not wait for the next scheduled appointment if any of those symptoms develop. If symptoms are severe, if blood pressure reads 160 over 110 or higher on a home cuff, or if you have a combination of symptoms, go to your nearest emergency department or call your local emergency number.

Rapid weight gain from fluid retention, more than 1 kilogram per week in the third trimester, is associated with preeclampsia, though it is not a specific sign and has other causes. Routine weighing at antenatal appointments partly serves this detection purpose.

| Symptom | Action |
|---|---|
| Persistent headache not relieved by paracetamol | Contact maternity unit same day |
| Visual disturbances: blurred vision, spots, flashing lights | Contact maternity unit same day |
| Sudden severe swelling of face or hands | Contact maternity unit same day |
| Upper abdominal pain, especially right side | Contact maternity unit same day |
| Home BP reading of 160 systolic or 110 diastolic or higher | Emergency department immediately |
| Combination of any severe symptoms | Emergency department immediately |
| Gradual ankle or foot swelling, no other symptoms | Normal in late pregnancy; raise at next appointment |

## What does "severe preeclampsia" mean, and why does it matter?

Preeclampsia is classified as having severe features when any of the following are present: a blood pressure of 160 over 110 mmHg or higher confirmed on two occasions; a platelet count below 100,000 per microlitre; impaired kidney function (creatinine above 97 micromol per litre or a doubling of baseline); liver enzyme levels more than twice the upper limit of normal; pulmonary oedema; or new-onset severe headache or visual disturbances not explained by another cause. Severe features indicate that the condition has extended beyond elevated blood pressure alone to involve other organ systems. ([Practice Bulletin 222, ACOG, 2020](https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2020/06/gestational-hypertension-and-preeclampsia))

HELLP syndrome, an acronym for Haemolysis, Elevated Liver enzymes, and Low Platelets, is a severe variant that occurs in approximately 10 to 20 percent of preeclampsia cases with severe features. It is a medical emergency. The presenting symptoms, including nausea, vomiting, and right-sided upper abdominal pain, can be mistaken for other conditions. HELLP can develop without classic blood pressure thresholds being met. Any of those symptoms in the second half of pregnancy, especially in combination, warrant urgent assessment. ([The HELLP syndrome: Clinical issues and management, PMC, 2009, PMC2654858](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2654858/))

Eclampsia, the occurrence of grand mal seizures in a woman with preeclampsia, is the most serious acute complication. The Magpie Trial, an RCT of over 10,000 women across 33 countries, found that magnesium sulphate reduced the risk of eclampsia by 58 percent compared with placebo and is now standard care for severe preeclampsia. Eclampsia occurs at a rate of approximately 8.6 per 10,000 births in Australia. ([Magpie Trial, The Lancet, 2002, PMC follow-up PMC1974836](https://pmc.ncbi.nlm.nih.gov/articles/PMC1974836/); [Eclampsia in Australia and New Zealand: prospective population-based study, PMID 31840809](https://pubmed.ncbi.nlm.nih.gov/31840809/))

## What happens when preeclampsia is diagnosed?

Management depends on gestational age and severity. Delivery of the placenta is the only treatment that resolves preeclampsia. There is no medication or dietary intervention that cures it. All clinical management before term is about balancing the maternal risk of continuing the pregnancy against the neonatal risk of premature birth. ([Practice Bulletin 222, ACOG, 2020](https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2020/06/gestational-hypertension-and-preeclampsia))

For preeclampsia without severe features diagnosed at or after 37 weeks, ACOG recommends delivery rather than expectant management, because the benefit of continuing the pregnancy does not outweigh the escalating risk. Before 37 weeks, close monitoring is required, typically as a hospital inpatient. Blood pressure is treated with antihypertensive medication when readings reach 160 over 110 or higher. The agents used in Australia include labetalol, nifedipine, and hydralazine; ACE inhibitors and angiotensin receptor blockers are contraindicated in pregnancy. Magnesium sulphate is given in severe cases to prevent eclampsia. If delivery before 34 weeks is anticipated, corticosteroids are given to accelerate fetal lung maturation. ([ACOG Committee Opinion, Antenatal Corticosteroid Therapy for Fetal Maturation, 2017](https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/08/antenatal-corticosteroid-therapy-for-fetal-maturation))

When severe features develop or cannot be controlled, delivery is indicated regardless of gestational age. This is why preeclampsia is associated with prematurity and neonatal intensive care admission. The decision to deliver early reflects the evidence that uncontrolled severe preeclampsia carries greater maternal and fetal risk than the risks of prematurity at the same gestational age.

Symptoms often improve within hours of delivery. Blood pressure usually normalises within six weeks, though some women remain hypertensive for longer and need antihypertensive medication in the postnatal period. The risk window for severe complications including eclampsia extends 48 to 72 hours after delivery, which is why postnatal monitoring matters. Any new severe symptoms after discharge from hospital should be assessed urgently.

## Does preeclampsia affect your health after pregnancy?

The evidence on this is consistent and strong. A history of preeclampsia is associated with substantially elevated lifetime cardiovascular risk. The landmark 2007 systematic review and meta-analysis by Bellamy and colleagues, published in the BMJ, included over 3.4 million women and found the following relative risks in the years following preeclampsia: hypertension at 3.7 times, ischaemic heart disease at 2.2 times, stroke at 1.8 times, and cardiovascular death at 2.3 times compared with women who had uncomplicated pregnancies. ([Bellamy L et al., Pre-eclampsia and risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis, BMJ, 2007, PMID 17975258](https://pubmed.ncbi.nlm.nih.gov/17975258/)) A 2025 update confirmed a 2.5 times elevated risk for heart failure specifically, and found the elevated cardiovascular risk becomes clinically apparent as early as 5 to 10 years after delivery and persists for decades. ([Long-term cardiovascular risk and maternal history of pre-eclampsia, PMC, 2025, PMC12072551](https://pmc.ncbi.nlm.nih.gov/articles/PMC12072551/))

This elevated risk is not fully explained by shared underlying risk factors. Preeclampsia is understood as both a consequence and a marker of cardiovascular susceptibility, with evidence that the condition itself causes lasting endothelial dysfunction and accelerates atherosclerosis.

ACOG and NICE both recommend that clinicians inform women who have had preeclampsia of this long-term risk. Annual blood pressure monitoring, a fasting lipid profile, and blood sugar testing are recommended throughout life. At your six-week postnatal check, mention the preeclampsia diagnosis to your GP so this monitoring can begin. Lifestyle factors that reduce cardiovascular risk, including not smoking, regular physical activity, and maintaining a healthy weight, have real benefit in this population.

## What myCocoon does and doesn't do with your blood pressure readings

**Preeclampsia can look like nothing until it doesn't, and the guidance above only helps if you remember it the moment a symptom shows up.** We built myCocoon for that moment. Tell it what you're feeling, and it knows when a combination of symptoms is worth an emergency prompt rather than wait and see.

If you have a home blood pressure cuff that syncs readings to the Apple Health app, myCocoon reads those values with your permission. Blood pressure readings are stored in a part of the app that is set up to never sync to iCloud or CloudKit. Apple's HealthKit guidelines prohibit storing health data in iCloud, and the app follows that rule. Blood pressure data is also not included in the information sent to Google's Gemini when Cloud AI is turned on. The privacy page at trymycocoon.com names exactly what is and is not sent.

The home screen's daily vitals card shows your most recent systolic and diastolic readings alongside other health signals. If your systolic reading is 140 mmHg or higher, the health signal is marked as elevated, following the ACOG threshold from Practice Bulletin 222. This is a display flag, not a clinical assessment. It notes that the reading is above the recognised monitoring threshold. The clinical assessment belongs with your midwife or GP.

The AI assistant inside myCocoon has a safety gate that checks for preeclampsia-associated symptom combinations before any AI model is involved. A message mentioning severe headache alongside sudden swelling, for example, triggers an immediate emergency card reading "Possible Preeclampsia Signs" and directs you to contact your maternity unit or go to emergency immediately. This check runs locally, with no latency and no cloud call.

What the app does not do: it does not diagnose preeclampsia, provide clinical blood pressure monitoring, or replace any part of antenatal care. It surfaces HealthKit readings, flags the recognised threshold, and raises an emergency prompt when your message combines known warning sign patterns. The clinical judgement is your care team's to make.

myCocoon is live on the App Store now, on iPhone with iOS 26 or later. It is smaller and newer than apps like Flo or What to Expect, with no Android version and no community feed. What it gives you instead is a companion that already has your numbers when a question arrives, keeps your health data on your device by default, runs no ads, and charges a flat subscription.

## Common questions

**What blood pressure reading counts as preeclampsia?**
A systolic reading of 140 mmHg or higher, or a diastolic of 90 mmHg or higher, confirmed on two separate occasions at least four hours apart, after 20 weeks of pregnancy. Preeclampsia also requires either protein in the urine or signs of organ involvement such as abnormal liver or kidney function, a low platelet count, severe headache, or visual disturbances. High blood pressure alone without those features is classified as gestational hypertension.

**Can preeclampsia be prevented with aspirin?**
For women with one or more high-risk factors, low-dose aspirin started before 16 weeks of pregnancy reduces the risk of preterm preeclampsia. The ASPRE trial found a 62 percent reduction in preterm preeclampsia with 150 mg aspirin per day started at 11 to 14 weeks. RANZCOG and SOMANZ recommend 100 to 150 mg per day for Australian women; ACOG and the USPSTF recommend 81 mg per day. Discuss it at your first antenatal appointment.

**Can preeclampsia come on suddenly?**
Yes. The condition can progress from mild to severe features within hours or days. Persistent headache not relieved by paracetamol, visual disturbances, sudden face or hand swelling, or upper abdominal pain are reasons to contact your maternity unit the same day. For very high blood pressure or a combination of those symptoms, go to emergency immediately.

**Will I have preeclampsia again in a future pregnancy?**
A history of preeclampsia, particularly early-onset preeclampsia requiring delivery before 34 weeks, is a high-risk factor for recurrence. The recurrence rate is higher with earlier and more severe first episodes. A prior preeclampsia diagnosis carries a relative risk of approximately 8.4 for a subsequent episode. Low-dose aspirin started before 16 weeks in a subsequent pregnancy is recommended by both ACOG and RANZCOG.

**Is preeclampsia dangerous for the baby?**
Yes. Preeclampsia is associated with fetal growth restriction, as the placenta may not function well under the condition's vascular stress. It also causes prematurity when delivery is indicated early, and low birth weight. In severe cases, early delivery may be the right decision for both mother and baby, even at a gestational age where prematurity carries real risk. Fetal growth and wellbeing are monitored closely as part of management.

**Can I have preeclampsia without any symptoms?**
Yes. Many women with preeclampsia, especially in early stages, have no noticeable symptoms at all. High blood pressure typically causes no pain or discomfort. This is why blood pressure is checked at every antenatal appointment, and one of the strongest reasons to attend those appointments even when you feel well.

## Bottom line

Preeclampsia develops in roughly 3 to 4 percent of pregnancies in Australia after 20 weeks. It is identified primarily through blood pressure checks and urine tests at antenatal appointments, not by how you feel. If you have a prior history of preeclampsia, are carrying multiples, or have chronic hypertension or diabetes, ask your GP or midwife about low-dose aspirin before 16 weeks, and make sure they know which dose is appropriate for you. Learn the severe-features symptoms: persistent headache not relieved by paracetamol, visual disturbances, sudden swelling of the face or hands, and upper abdominal pain. Any of those: call your maternity unit the same day. Severe readings or a combination of symptoms: go to emergency. The condition resolves with delivery, though the postnatal monitoring window extends to 48 to 72 hours. After pregnancy, tell your GP about the history so long-term cardiovascular monitoring can begin.

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