Hypertensive disorders of pregnancy

Red Flags

Severe hypertension (SBP ≥160 or DBP ≥110 mm Hg) sustained ≥15 minutes — admit; treat within 30–60 minutes; magnesium sulfate if pre-eclampsia features^[1]
Eclampsia (seizure in pregnancy or up to 6 weeks postpartum) — emergency; magnesium sulfate; controlled BP; deliver after stabilisation^[1]
HELLP syndrome (haemolysis, elevated liver enzymes, low platelets) — admit; deliver per gestation; corticosteroid for fetal lung maturity 24–34 weeks^[1]
Severe headache, visual disturbance, epigastric pain, or oliguria — emergency review for impending eclampsia or HELLP^[1]

Aspirin prophylaxis from 12 weeks^[1]
81–162 mg PO daily from 12+0 to 28+0 weeks (continue to delivery in some pathways) for women at high risk: prior PE, chronic HTN, T1/T2DM, autoimmune disease, twins, BMI ≥35, age ≥35, or ≥2 moderate-risk factors
Antenatal management stratified by severity^[1]
Mild gestational HTN: outpatient monitoring weekly. Pre-eclampsia without severe features: weekly twice-bloods, biweekly maternal/fetal surveillance, deliver 37 weeks. With severe features: admit, deliver after stabilisation if ≥34 weeks
Timing of delivery^[1]
Gestational HTN: 37 weeks. Pre-eclampsia without severe features: 37 weeks. Pre-eclampsia with severe features: 34 weeks (after stabilisation, magnesium, antihypertensive, betamethasone if 24–34 weeks). Eclampsia: deliver after seizure control
Postpartum surveillance^[1]
Monitor BP for ≥72 h post-delivery and again at 7–10 days; pre-eclampsia can present de novo postpartum; continue antihypertensive titration; prepare for long-term cardiovascular risk follow-up

Drug	Class	Adult	Paediatric	Notes
Labetalol (oral or IV)^[1]	Combined alpha-1 / non-selective beta-blocker	Oral 100–200 mg PO BD-TDS, max 1200 mg/day. IV severe HTN: 20 mg IV bolus, repeat 40, 80 mg every 10 min (max 220 mg)	—	First-line in pregnancy; avoid in asthma, bradycardia, heart block; safe in breastfeeding
Nifedipine^[1]	Calcium channel blocker (DHP)	Immediate-release 10 mg PO for severe acute HTN (repeat at 20 min if needed); ER 30–60 mg PO daily for maintenance	—	First-line maintenance; useful in asthma; combine with labetalol for resistant; do not use sublingual immediate-release
Hydralazine (severe acute HTN)^[1]	Direct arterial vasodilator	5 mg IV bolus, repeat 5–10 mg every 20 min (max 30 mg) or infusion 0.5–10 mg/h	—	Severe pregnancy hypertension when labetalol contraindicated or not available; reflex tachycardia, headache
Magnesium sulfate (eclampsia prevention and treatment)^[1]	Anticonvulsant / NMDA modulator	Loading 4–6 g IV over 15–20 min, maintenance 1–2 g/h IV for 24 h after delivery or last seizure	—	Severe pre-eclampsia and eclampsia; monitor patellar reflex, respiratory rate, urine output; calcium gluconate antidote for toxicity

Labetalol (oral or IV)^[1]

Combined alpha-1 / non-selective beta-blocker

Adult: Oral 100–200 mg PO BD-TDS, max 1200 mg/day. IV severe HTN: 20 mg IV bolus, repeat 40, 80 mg every 10 min (max 220 mg)
Paediatric: —

First-line in pregnancy; avoid in asthma, bradycardia, heart block; safe in breastfeeding

Nifedipine^[1]

Calcium channel blocker (DHP)

Adult: Immediate-release 10 mg PO for severe acute HTN (repeat at 20 min if needed); ER 30–60 mg PO daily for maintenance
Paediatric: —

First-line maintenance; useful in asthma; combine with labetalol for resistant; do not use sublingual immediate-release

Hydralazine (severe acute HTN)^[1]

Direct arterial vasodilator

Adult: 5 mg IV bolus, repeat 5–10 mg every 20 min (max 30 mg) or infusion 0.5–10 mg/h
Paediatric: —

Severe pregnancy hypertension when labetalol contraindicated or not available; reflex tachycardia, headache

Magnesium sulfate (eclampsia prevention and treatment)^[1]

Anticonvulsant / NMDA modulator

Adult: Loading 4–6 g IV over 15–20 min, maintenance 1–2 g/h IV for 24 h after delivery or last seizure
Paediatric: —

Severe pre-eclampsia and eclampsia; monitor patellar reflex, respiratory rate, urine output; calcium gluconate antidote for toxicity

Severe headache, vision changes, epigastric pain, vomiting, rapid swelling, or reduced fetal movements — call your maternity unit same day; these can precede eclampsia^[1]
Pre-eclampsia can present up to 6 weeks postpartum — monitor BP for 6 weeks after delivery and report severe headache or hypertensive symptoms^[1]
After a pregnancy with hypertension, your long-term cardiovascular risk is increased — annual BP, lipid, and diabetes screening are recommended^[1]

Severe hypertension (≥160/110), eclampsia, HELLP, or impending eclampsiaEmergency obstetric admission; HDU/ITU^[1]
Pre-eclampsia (any severity)Obstetric admission per protocol; senior obstetric input^[1]
Chronic hypertension planning pregnancy or in early pregnancyJoint preconception/obstetric clinic; switch to pregnancy-safe agent^[1]
Postpartum hypertension persisting beyond 12 weeksHypertension clinic for chronic HTN management^[1]

Diagnosis and management of gestational hypertension, pre-eclampsia, eclampsia, and chronic hypertension in pregnancy and postpartum.

1.ACOG Practice Bulletin No. 222 — Gestational Hypertension and Preeclampsia (2020, reaffirmed 2024); ACOG Committee Opinion 743 on Aspirin Use (2020)