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What the guideline actually says

Written for the person holding the cuff, not the person writing the protocol. Every article is a translation of SOMANZ 2023 — not advice about you.

What counts as high blood pressure in pregnancy

The SOMANZ numbers, and why one reading is a signal rather than a label.

The threshold

SOMANZ 2023 defines hypertension in pregnancy as a systolic blood pressure of 140 mmHg or more, and/or a diastolic of 90 mmHg or more. Those numbers should be confirmed — three readings at least two minutes apart, then repeated over a minimum of four hours — before anyone calls it a diagnosis. Willow will still treat a single high home reading as a reason to contact your team.

Severe is different

A reading of 160 systolic or 110 diastolic or higher is acute hypertension. That is treated as an emergency, in hospital, aiming to bring the pressure below 160/110. Do not wait to message a companion app.

The usual target if you already have a diagnosis

For gestational or chronic hypertension, SOMANZ recommends tight control to ≤ 135/85 mmHg. That target was chosen because it helps the mother without evidence of harm to the baby.

The six names your team might use

Preeclampsia is only one of the hypertensive disorders of pregnancy.

Why the name matters

The plan for surveillance, medicines, and timing of birth changes with the classification. Willow can explain the definitions. Only your team can apply one to you.

The list

Preeclampsia, gestational hypertension, chronic hypertension, superimposed preeclampsia, white-coat hypertension, and — new as a formal category in 2023 — masked hypertension. Masked means clinic readings look fine while home readings are high. White-coat is the reverse.

Preeclampsia, in plain language

Hypertension after 20 weeks plus a sign that another organ, or the placenta, is involved.

Protein in the urine is not the whole story

Many people still hear that preeclampsia 'is high blood pressure plus protein'. SOMANZ is explicit: proteinuria is common, and a uPCR of 30 mg/mmol or more counts as renal involvement, but it is not required. Liver, blood, brain, lungs, or the placenta can complete the definition instead.

Symptoms that must not wait

A persistent or severe headache, visual change, pain under the ribs, sudden swelling, trouble breathing, a fit, or a baby that is moving less — these are reasons to seek care now, not to keep reading.

A blood test that can rule out, not rule in

Where it is available quickly, an sFlt-1 to PlGF ratio below 38 after 20 weeks can help rule out preeclampsia for one to four weeks in someone already under suspicion. It does not replace examination, and a high ratio is not used on its own to make the diagnosis.

Prevention: aspirin, calcium, movement

Start with risk. Then talk to your team before 16 weeks if you can.

Who is offered prevention

One high-risk factor — previous hypertensive disorder, kidney disease, twins, chronic hypertension, pre-existing diabetes, or autoimmune disease such as lupus or APS — is enough. So are two or more moderate factors: age over 40, BMI 35 or more, first baby, family history, a ten-year gap, IVF or other ART, or a resting blood pressure already over 130/80.

Aspirin

If you are in that group, SOMANZ strongly recommends aspirin 150 mg daily at bedtime, started before 16 weeks. Stopping is usually considered between 34 weeks and birth. Universal aspirin for low-risk first pregnancies is recommended against. Willow cannot prescribe or tell you to start a tablet tonight.

Calcium and exercise

Extra calcium is for people whose diet is under about a gram a day. Moderate activity for two and a half to five hours a week is recommended as ordinary pregnancy care.

How to take a blood pressure at home

A validated machine and a boring, repeatable ritual beat a single dramatic number.

The ritual

Sit, back supported, feet flat, cuff at heart level. Rest five minutes. Stay quiet. Take three readings two minutes apart. Write them down. If the first is high, the next two still matter.

What home monitoring is for

SOMANZ supports home or ambulatory readings, on validated machines, to pick up white-coat and masked hypertension, and to follow some people with chronic or gestational hypertension. It does not replace the minimum schedule of antenatal visits.

After the birth

Preeclampsia does not always leave with the placenta.

This week

You should be seen within a week of going home so that blood pressure is still stable. Keep taking prescribed antihypertensives until your team changes them. Enalapril is an extra option after birth, chosen with you if you are feeding.

Pain relief

SOMANZ conditionally recommends against routine NSAIDs such as ibuprofen after preeclampsia. Ask your team for an alternative rather than finishing a leftover packet.

The longer arc

Hypertensive disorders raise later risk of high blood pressure, heart disease, stroke, and kidney disease. A 3–6 month review of blood pressure, urine protein, weight, and metabolic bloods, then yearly checks, is the SOMANZ practice point. Mood should be asked about every time. A later pregnancy deserves a pre-conception plan and a conversation about aspirin.

Medicines the guideline names

Named so you can recognise them. Not so you can start, stop, or titrate anything from this page.

Labetalol

A common first-line oral agent for stable hypertension. Not suitable for some people with asthma. Your team chooses the dose.

Nifedipine

A calcium-channel blocker used for stable hypertension. Immediate-release nifedipine is reserved for acute severe hypertension in hospital.

Methyldopa

A long-used oral option in pregnancy. Choice is individual and shared.

Acute hypertension (≥ 160/110 mmHg) is treated in hospital with short-acting agents such as IV hydralazine, IV labetalol, oral immediate-release nifedipine, or IV diazoxide — whichever the unit knows well. Target is below 160/110. Magnesium sulfate is strongly recommended if there is a risk of eclampsia.

The six classifications

Preeclampsia

New hypertension after 20 weeks plus organ or placental involvement

A multisystem disorder. Proteinuria is common but not required. Involvement can be renal (uPCR ≥ 30 mg/mmol or creatinine > 90 µmol/L), liver (raised transaminases), haematological (platelets < 150 × 10⁹/L or haemolysis), neurological (seizure, persistent headache, visual change), pulmonary oedema, or placental (growth restriction with abnormal Dopplers or oligohydramnios).

Gestational hypertension

New hypertension after 20 weeks, without preeclampsia features

Blood pressure returns to normal within three months after birth. It can still progress to preeclampsia, so close surveillance matters.

Chronic hypertension

Hypertension before pregnancy, or before 20 weeks

Includes women already treated for high blood pressure. Superimposed preeclampsia is diagnosed if preeclampsia features appear after 20 weeks.

Superimposed preeclampsia

Preeclampsia features on chronic hypertension or known kidney disease

After 20 weeks, new organ or placental involvement on a background of chronic hypertension and/or pre-existing renal disease.

White-coat hypertension

High in clinic, normal at home

Raised readings with a clinician present, normal on validated home or ambulatory monitoring. Still needs a plan — it is a recognised HDP category.

Masked hypertension

Normal in clinic, high at home

New in SOMANZ 2023 as a formal category. Home or ambulatory readings are high while clinic readings look normal. Easy to miss without home monitoring.

After birth

Preeclampsia and gestational hypertension raise later risk of hypertension, heart disease, stroke, and kidney disease.
You should be reviewed within a week of leaving hospital so blood pressure is still stable at home.
Antenatal antihypertensives can continue after birth; enalapril is an additional option postpartum, chosen with your team, especially if you are breastfeeding.
SOMANZ conditionally recommends against routine NSAIDs (for example ibuprofen) after preeclampsia until more safety data exist.
At 3–6 months: blood pressure, urine protein, BMI, and a metabolic profile. Yearly review for 5–10 years is reasonable.
Ask about mood at every visit. Pre-conception planning and aspirin in a later pregnancy matter.

SOMANZ Hypertension in Pregnancy Guideline 2023 (NHMRC-approved). Summary: Shanmugalingam et al., Med J Aust 2024. Willow is an educational proof of concept and is not affiliated with SOMANZ.