ObstetricsTier 1Disease (DEADMAN)

Gestational hypertension

Description

Classification (ISSHP 2021 / SOMANZ 2023)

Category	Definition
Chronic HTN	Present before pregnancy or diagnosed <20 weeks
Gestational HTN	New HTN >=20 weeks, no maternal/fetal features of pre-eclampsia
Pre-eclampsia	New HTN >=20 weeks + maternal organ dysfunction and/or fetal growth restriction
Chronic HTN + superimposed pre-eclampsia	New organ dysfunction/proteinuria on a background of chronic HTN
White-coat / masked HTN	Clinic vs home discordance - confirm with home/ambulatory BP

Proteinuria is no longer required for pre-eclampsia diagnosis - organ dysfunction (renal, hepatic, neurological, haematological) or FGR suffices
~15-25% of gestational HTN progresses to pre-eclampsia, more if early onset (<34 weeks)

Hypertensive disorders complicate ~5-10% of pregnancies
Gestational HTN ~6-8%; pre-eclampsia ~2-5%
Risk factors: nulliparity, prior pre-eclampsia, chronic HTN, pregestational DM, BMI >30, antiphospholipid syndrome, multiple pregnancy, age >40, family history, interpregnancy interval >10 years

Two-stage model
- Stage 1: abnormal trophoblastic invasion of spiral arteries -> failed physiological remodelling -> placental hypoperfusion
- Stage 2: placental release of anti-angiogenic factors (sFlt-1 up, PlGF down) -> systemic endothelial dysfunction
Endothelial dysfunction -> vasospasm, inc vascular permeability, activation of coagulation
- -> HTN, proteinuria, oedema, and end-organ effects (liver, kidney, brain, placenta)
Gestational HTN without organ dysfunction may reflect a milder/later version of the same spectrum, or an unrelated predisposition to HTN unmasked by pregnancy

Blood pressure

Pre-eclampsia work-up once HTN identified >=20 weeks

Urine PCR or ACR (proteinuria supportive but not required)
FBE (platelets, haemolysis film), UEC, urate, LFT
Angiogenic markers (sFlt-1:PlGF ratio) - where available, high negative predictive value for excluding pre-eclampsia within 1-2 weeks
CTG, growth ultrasound + umbilical artery Dopplers - assess fetal wellbeing/FGR

Features defining severity/organ involvement

Renal: creatinine >90 umol/L or doubling, oliguria
Hepatic: transaminitis, epigastric/RUQ pain
Neurological: severe headache, visual disturbance, hyperreflexia/clonus, eclampsia
Haematological: platelets <150, haemolysis (HELLP), DIC
Uteroplacental: FGR, abnormal Dopplers, abruption

Prevention in high-risk women

Low-dose aspirin 100-150 mg nocte, started ideally <16 weeks (before 20 at latest), continued to 36 weeks
Calcium supplementation if low dietary intake

BP targets and agents

Target <=135/85 for gestational/chronic HTN
Oral agents: labetalol, methyldopa, oral nifedipine (modified release)
Avoid ACEi/ARB (fetotoxic - renal dysgenesis, oligohydramnios) and atenolol (FGR)

Acute severe hypertension (>=160/110) - emergency

IV labetalol, IV hydralazine, or oral immediate-release nifedipine - treat within 30-60 min
Continuous fetal monitoring during treatment

Pre-eclampsia

Magnesium sulfate - seizure prophylaxis if severe features/imminent eclampsia, and for eclampsia treatment (loading + maintenance infusion; monitor reflexes, respiratory rate, urine output for toxicity)
Corticosteroids for fetal lung maturation if birth anticipated <34-36 weeks
Definitive treatment = birth - timing balances maternal severity against gestation:
- Gestational HTN, well-controlled - term (37-40 weeks)
- Pre-eclampsia without severe features - by 37 weeks
- Severe features - expedite, often <34 weeks after stabilisation and steroids
HELLP/eclampsia/uncontrolled severe HTN - deliver regardless of gestation once maternal condition allows

Postpartum

HELLP syndrome, eclampsia, placental abruption
Fetal growth restriction, oligohydramnios, stillbirth
Preterm birth (iatrogenic)
Long-term maternal risk: cardiovascular disease and chronic HTN in later life (pre-eclampsia is a marker of future CV risk)

Gestational HTN - BP usually normalises within 12 weeks postpartum; if not, reclassify as chronic HTN
~15-25% of gestational HTN progresses to pre-eclampsia (higher if early onset)
Pre-eclampsia recurrence in future pregnancy ~15-20%, higher if early-onset/severe
Women with a hypertensive pregnancy disorder need lifelong cardiovascular risk factor surveillance

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