Hypertensive disorders are a leading cause of maternal and perinatal death worldwide. Stroke is a major cause of death from preeclampsia, so severe-range blood pressure is treated as an emergency.
Classification (ACOG)
| Disorder | Definition |
|---|
| Chronic hypertension | BP ≥ 140/90 mmHg before pregnancy or before 20 weeks, or persisting beyond 12 weeks postpartum |
| Gestational hypertension | New BP ≥ 140/90 mmHg on two occasions at least 4 hours apart after 20 weeks, in a previously normotensive client, without proteinuria or severe features |
| Preeclampsia | New hypertension after 20 weeks plus proteinuria, or, without proteinuria, new hypertension plus new thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or new headache/visual disturbances. Gestational hypertension with severe-range BP (≥ 160/110) is managed as preeclampsia with severe features |
| Preeclampsia with severe features | Preeclampsia with severe-range BP or end-organ involvement |
| Eclampsia | New-onset tonic–clonic seizures in a client with preeclampsia, not explained by another cause |
| HELLP syndrome | Hemolysis, Elevated Liver enzymes, Low Platelets — a severe form, sometimes with normal BP or no proteinuria |
| Chronic hypertension with superimposed preeclampsia | Preeclampsia developing in a client with chronic hypertension |
Proteinuria: ≥ 300 mg in 24 hours, or protein/creatinine ratio ≥ 0.3, or dipstick 2+ only when quantitative testing is unavailable.
Severe features (any one)
- Systolic BP ≥ 160 or diastolic ≥ 110 mmHg on two occasions at least 4 hours apart (confirmed within minutes when antihypertensive therapy is started earlier)
- Platelets < 100,000/µL (100 × 10⁹/L)
- Liver enzymes more than twice normal, or severe persistent right upper quadrant or epigastric pain
- Serum creatinine > 1.1 mg/dL (97 µmol/L) or doubling
- Pulmonary edema
- New headache not relieved by acetaminophen, or visual disturbances
Current rules that differ from older materials
- Edema is no longer a diagnostic criterion — it is common in normal pregnancy
- Proteinuria is not required when severe features are present
- The amount of proteinuria (e.g., ≥ 5 g/24 h) and fetal growth restriction are no longer severe features
Pathophysiology — abnormal placental development (shallow trophoblast invasion of the spiral arteries) → poorly perfused placenta releases antiangiogenic factors → widespread endothelial dysfunction and vasospasm:
- Kidneys → proteinuria, reduced GFR, oliguria
- Liver → periportal injury, capsule stretching (RUQ/epigastric pain), rupture (rare)
- Brain → headache, visual changes, hyperreflexia, seizures, stroke, posterior reversible encephalopathy
- Blood → hemoconcentration, thrombocytopenia, hemolysis, DIC
- Capillary leak → pulmonary edema despite reduced intravascular volume
- Placenta → fetal growth restriction, oligohydramnios, abruption
The only cure is delivery of the placenta, but preeclampsia can appear or worsen after birth (postpartum preeclampsia, usually within the first 1–2 weeks and up to 6 weeks).
Risk factors and aspirin prophylaxis
| High risk (any one → recommend aspirin) | Moderate risk (more than one → consider aspirin) |
|---|
| Previous preeclampsia | Nulliparity |
| Multifetal gestation | Obesity (BMI > 30) |
| Chronic hypertension | Family history of preeclampsia (mother or sister) |
| Pregestational diabetes (type 1 or 2) | Age 35 or older |
| Kidney disease | Black race (reflecting effects of racism) and low income |
| Autoimmune disease (SLE, antiphospholipid syndrome) | IVF pregnancy; prior low birth weight, adverse outcome, or more than 10-year pregnancy interval |
Low-dose aspirin 81 mg daily, started between 12 and 28 weeks (optimally before 16 weeks) and continued until delivery (USPSTF: after 12 weeks). Teach to report bleeding; aspirin is avoided with aspirin allergy or active bleeding disorders.
- Blood pressure — seated, feet supported, correctly sized cuff, arm at heart level, after rest; recheck high readings
- Neurologic: headache, visual changes (blurring, scotomata, flashing lights), altered mental status, deep tendon reflexes (DTRs) and clonus (hyperreflexia = cerebral irritability)
- Epigastric or RUQ pain, nausea, vomiting (liver involvement/HELLP)
- Respiratory: dyspnea, crackles, SpO₂ (pulmonary edema)
- Urine output (oliguria), weight gain, edema (face/hands — note but not diagnostic)
- Fetal: FHR pattern, fetal movement, growth, amniotic fluid
- Signs of abruption: abdominal pain, uterine tenderness, bleeding
- CBC with platelets, serum creatinine, AST/ALT, LDH, bilirubin; coagulation studies if platelets are low or abruption is suspected
- Urine protein/creatinine ratio or 24-hour urine protein
- HELLP: LDH ≥ 600 IU/L, AST and ALT more than twice normal, platelets < 100,000/µL (100 × 10⁹/L)
- Fetal: ultrasound for growth and fluid, umbilical artery Doppler, nonstress test/biophysical profile
- sFlt-1/PlGF ratio (a blood test of the antiangiogenic imbalance) is available in some centers to help predict progression to severe features within 2 weeks in hospitalized clients
Timing of birth
- Gestational hypertension or preeclampsia without severe features: expectant management with frequent maternal and fetal assessment; birth at 37 0/7 weeks
- Preeclampsia with severe features: birth at or after 34 0/7 weeks once the client is stabilized; before 34 weeks, expectant management only in selected stable cases at a tertiary center, with antenatal corticosteroids (delivery is not delayed for steroids after 34 weeks)
- Eclampsia, HELLP, pulmonary edema, abruption, uncontrollable BP, or abnormal fetal testing → birth after stabilization, regardless of gestational age
- Vaginal birth is often possible; neuraxial (epidural/spinal) anesthesia is generally preferred if platelets allow
Acute severe hypertension (≥ 160/110 mmHg persisting 15 minutes or more) — treat within 30–60 minutes
| Drug | Typical first dose | Key safety points |
|---|
| Labetalol IV | 20 mg IV over 2 minutes; escalate (40, then 80 mg) every 10 minutes; if still severe after 80 mg, switch to hydralazine (maximum cumulative labetalol 300 mg) | Avoid in asthma, heart failure, heart block, bradycardia; neonatal bradycardia possible |
| Hydralazine IV | 5–10 mg IV over 2 minutes; recheck BP in 20 minutes → if still severe, 10 mg IV; if still severe 20 minutes later, switch to IV labetalol and obtain specialist (maternal-fetal medicine, anesthesia) consultation | Maternal hypotension (can drop placental perfusion), reflex tachycardia, headache |
| Nifedipine (immediate-release, oral) | 10 mg orally, then 20 mg after 20 minutes, then 20 mg; if still severe, switch to IV labetalol | Headache, flushing, reflex tachycardia; swallow — not sublingual |
Monitor BP every 10–20 minutes during treatment and continuous FHR. Aim for gradual reduction (e.g., to 140–150/90–100 mmHg), avoiding hypotension.
Chronic hypertension — treat to keep BP below 140/90 mmHg (ACOG 2022 based on the CHAP trial). Preferred oral drugs: labetalol, extended-release nifedipine; methyldopa is an alternative. ACE inhibitors, ARBs, and direct renin inhibitors are contraindicated (fetal kidney damage). Continue low-dose aspirin.
Magnesium sulfate — seizure prophylaxis and treatment
- Given for preeclampsia with severe features, eclampsia, and HELLP (ACOG does not require it for all clients without severe features). It prevents seizures; it is not an antihypertensive
- IV loading dose 4–6 g over 20–30 minutes, then 1–2 g/hour, via infusion pump on a secondary line; continue for 24 hours after birth
- IM alternative when IV access fails: 10 g (5 g in each buttock), then 5 g every 4 hours
- Excreted by the kidneys — reduce the dose and check serum levels with oliguria or raised creatinine
- Contraindicated in myasthenia gravis; interactions: potentiates neuromuscular blockers; calcium channel blockers may be used together with monitoring
- Expected effects: flushing, warmth, nausea, drowsiness, muscle weakness; newborn may be hypotonic or drowsy
- Continuous use for more than 5–7 days (e.g., prolonged tocolysis) can cause fetal hypocalcemia and bone abnormalities (FDA)
Magnesium levels and toxicity
| Serum magnesium | Effect |
|---|
| About 4.8–9.6 mg/dL (4–8 mEq/L; 2–4 mmol/L) | Range commonly quoted as therapeutic |
| About 9 mg/dL (7 mEq/L; 3.5 mmol/L) | Loss of patellar reflexes |
| About 12 mg/dL (10 mEq/L; 5 mmol/L) | Respiratory depression |
| About 30 mg/dL (25 mEq/L; 12.5 mmol/L) | Cardiac arrest |
Clinical signs (reflexes, respirations, urine output, consciousness) guide routine monitoring; serum levels are checked when toxicity is suspected or kidney function is impaired.
Antidote: calcium gluconate 10%, 10 mL (1 g) IV over about 3 minutes.
Listed in priority order.
- Eclamptic seizure
- Call for help; turn the client to the side (lateral), protect from injury, keep the airway clear — do not restrain and do not put anything in the mouth
- After the seizure: suction, oxygen, SpO₂; give magnesium sulfate (bolus, or an additional 2 g if already on an infusion) as ordered
- Fetal bradycardia during the seizure usually recovers within minutes; stabilize the mother before any decision to deliver
- Treat severe-range BP within 30–60 minutes per protocol; notify the provider immediately
- Magnesium safety monitoring (at least hourly during infusion)
- Respiratory rate (report < 12/min), SpO₂, DTRs (present), level of consciousness, BP
- Urine output — indwelling catheter; report < 30 mL/h (magnesium accumulates)
- If toxicity (absent reflexes, RR < 12, drowsiness, chest pain, low SpO₂): stop the infusion, call the provider, give calcium gluconate as ordered, support breathing
- Keep calcium gluconate and resuscitation equipment at the bedside
- Fluid management — strict intake and output; total IV and oral fluids are limited (commonly about 80–100 mL/h total, per order) to prevent pulmonary edema; do not "restrict" to the point of dehydration, and do not give large boluses; auscultate lungs regularly
- Seizure precautions — quiet, calm environment with low lighting, limited stimulation, padded side rails, suction and oxygen at bedside, bed low
- Monitor for complications — headache, visual change, epigastric pain, dyspnea, bleeding, decreased urine output, abdominal pain (abruption)
- Fetal surveillance — continuous FHR monitoring during acute management
- Postpartum — continue magnesium for 24 hours; BP monitoring; uterine atony risk (magnesium relaxes smooth muscle) — check fundus and bleeding
- Warning signs — seek care immediately (during pregnancy and for 6 weeks after birth): severe headache, vision changes, pain under the ribs on the right or in the upper abdomen, shortness of breath, sudden swelling of face or hands, seizure, decreased fetal movement
- Home BP monitoring with a validated device if prescribed; report readings ≥ 160/110 immediately and ≥ 140/90 per plan
- Take low-dose aspirin nightly if prescribed until delivery
- Keep all visits and fetal testing appointments
- After birth: BP check within 72 hours if severe hypertension and by 7–10 days for all hypertensive disorders (visit or remote monitoring); preeclampsia can occur after discharge
- NSAIDs (e.g., ibuprofen) are generally acceptable for postpartum pain, even with hypertension, per ACOG
- Long-term: HDP increase lifetime risk of hypertension, heart disease, stroke, and kidney disease — yearly BP, weight, lipids, and glucose checks; healthy lifestyle; preeclampsia may recur in future pregnancies (aspirin next time)
- Most antihypertensives used postpartum (labetalol, nifedipine, enalapril) are compatible with breastfeeding
| Complication | What to watch for |
|---|
| Eclampsia | Seizure; often preceded by headache, visual change, hyperreflexia/clonus |
| Stroke (hemorrhagic) | Severe headache, neurologic deficit — severe-range BP must be treated quickly |
| Pulmonary edema | Dyspnea, crackles, falling SpO₂ |
| HELLP / liver hematoma or rupture | RUQ pain, nausea, shoulder pain, shock |
| Placental abruption | Pain, uterine tenderness, bleeding, fetal distress |
| DIC | Oozing, low platelets and fibrinogen |
| Acute kidney injury | Oliguria, rising creatinine |
| Magnesium toxicity | Loss of DTRs, RR < 12, drowsiness |
| Fetal growth restriction, preterm birth | Small fundal height, abnormal testing |
- Preeclampsia = BP ≥ 140/90 after 20 weeks + proteinuria (or new organ dysfunction); edema is not a criterion
- Severe features: BP ≥ 160/110, platelets < 100,000, LFTs > 2× normal / RUQ pain, creatinine > 1.1 mg/dL (97 µmol/L), pulmonary edema, headache or visual disturbance
- First assessment in a client with preeclampsia: headache, visual change, epigastric/RUQ pain
- HELLP = hemolysis (LDH ≥ 600), elevated liver enzymes, low platelets
- Severe BP → IV labetalol, IV hydralazine, or oral immediate-release nifedipine within 30–60 minutes; ACE inhibitors/ARBs contraindicated in pregnancy
- Magnesium sulfate prevents seizures — 4–6 g load, 1–2 g/h, 24 hours postpartum
- Magnesium toxicity: loss of DTRs first, then respiratory depression → stop infusion, give calcium gluconate 1 g IV
- Monitor RR ≥ 12, DTRs present, urine output ≥ 30 mL/h
- Eclamptic seizure: side-lying, airway, do not restrain, magnesium
- Aspirin 81 mg from 12–28 weeks (ideally before 16) for one high-risk or more than one moderate-risk factor
- Birth: 37 weeks without severe features; 34 weeks with severe features
- Postpartum preeclampsia occurs; BP check within 72 hours (severe hypertension) and by 7–10 days (all HDP); lifelong cardiovascular risk
Country Notes
United States
- ACOG and AIM (Alliance for Innovation on Maternal Health) safety bundles call for treating severe-range BP within 60 minutes; many units use standardized order sets.
- Chronic hypertension in pregnancy is treated at 140/90 mmHg following the 2022 CHAP-based ACOG advisory.
Philippines
- Magnesium sulfate may be given by the IM route (10 g loading, then 5 g every 4 hours) where continuous IV infusion pumps are limited; monitoring of reflexes, respiration, and urine output is the same.
- The WHO recommends calcium supplementation (1.5–2 g elemental calcium daily) in pregnancy for populations with low dietary calcium intake, to reduce preeclampsia risk — follow DOH/local guidance.