How should hypertension in a pregnant patient be classified, evaluated, and managed—including target blood pressure goals, safe first‑line antihypertensive agents, contraindicated medications, treatment of severe hypertension, lifestyle measures, fetal surveillance, and timing of delivery?

Management of Hypertension in Pregnancy

Initiate antihypertensive treatment when blood pressure is consistently ≥140/90 mmHg (or ≥135/85 mmHg at home), targeting a diastolic BP of 85 mmHg and systolic BP of 110–140 mmHg, using methyldopa, labetalol, or long-acting nifedipine as first-line agents. 1, 2, 3

Classification

Hypertensive disorders in pregnancy fall into distinct categories that guide management:

• Chronic hypertension is present before pregnancy or diagnosed before 20 weeks' gestation 1, 4, 3
• Gestational hypertension is new-onset hypertension after 20 weeks without proteinuria; approximately 25% will progress to preeclampsia 1, 2, 4
• Preeclampsia is gestational hypertension accompanied by new maternal organ dysfunction (proteinuria, renal insufficiency, liver involvement, neurological complications, hematological complications, or uteroplacental dysfunction) 4, 3
• Superimposed preeclampsia occurs when chronic hypertension is complicated by new-onset proteinuria or worsening hypertension after 20 weeks 3
• White-coat hypertension is elevated clinic BP but normal home or ambulatory BP 4

Note that proteinuria is present in only 75% of preeclampsia cases and is not required for diagnosis 4. Hypertension detected before 20 weeks does not necessarily indicate chronic hypertension, as 61% of such cases represent early gestational hypertension 5.

Blood Pressure Thresholds and Targets

Non-Severe Hypertension

• Start pharmacological treatment at BP ≥140/90 mmHg (office) or ≥135/85 mmHg (home) 1, 2, 3
• Target diastolic BP of 85 mmHg and systolic BP of 110–140 mmHg 1, 2, 3
• Reduce or cease antihypertensives if diastolic BP falls below 80 mmHg 1
• This approach is supported by the CHIPS trial, which demonstrated reduced likelihood of accelerated maternal hypertension without adverse fetal outcomes 1, 3

Severe Hypertension (Hypertensive Emergency)

• BP ≥160/110 mmHg requires urgent treatment within 30–60 minutes in a monitored setting 1, 2, 4
• Confirmation requires repeat measurement within 15 minutes 4
• This threshold represents increased stroke risk and mandates immediate intervention 2, 4

First-Line Antihypertensive Medications

Safe agents for ongoing BP control:

• Methyldopa – drug of choice with established safety profile 1, 2, 3
• Labetalol – comparable efficacy to methyldopa; avoid concomitant use with calcium channel blockers due to severe hypotension risk 1, 3
• Long-acting nifedipine – effective for chronic control 1, 2, 3
• Oxprenolol – acceptable alternative 1

Second- or third-line agents:

• Hydralazine and prazosin 1

Acute Management of Severe Hypertension

For BP ≥160/110 mmHg, use one of the following in a monitored setting:

• Oral nifedipine (immediate-release) 1, 2
• Intravenous labetalol 1, 2
• Intravenous hydralazine 1, 2

Contraindicated Medications

• ACE inhibitors and angiotensin II receptor blockers are absolutely contraindicated due to fetopathy risk 6
• Atenolol should be avoided except in late pregnancy 6

Evaluation and Monitoring

Initial Assessment for Chronic Hypertension

All women with chronic hypertension require baseline testing to detect superimposed preeclampsia 4, 3:

• Complete blood count (including platelet count) 4, 3
• Liver enzymes (AST, ALT, LDH) 4, 3
• Serum creatinine, electrolytes, uric acid 4, 3
• Urinalysis with protein-to-creatinine or albumin-to-creatinine ratio 4, 3

Ongoing Monitoring for Gestational Hypertension

• Urinalysis at each visit to detect proteinuria 1
• Blood tests (hemoglobin, platelet count, liver transaminases, uric acid, creatinine) at minimum at 28 and 34 weeks 1
• Fetal ultrasound from 26 weeks, then every 2–4 weeks if normal 1
• Home BP monitoring is useful; verify device accuracy as approximately 25% differ from standard sphygmomanometry 1, 4

Monitoring for Preeclampsia

• BP monitoring with repeated assessments for proteinuria if not already present 1
• Clinical assessment including clonus 1
• Twice-weekly blood tests for hemoglobin, platelet count, liver transaminases, creatinine, and uric acid 1
• Fetal biometry, amniotic fluid, and umbilical artery Doppler at diagnosis, then every 2 weeks if normal 1

Indications for Hospitalization

Admit immediately for any of the following 1, 2, 4:

• BP ≥160/110 mmHg (severe hypertension) 1, 2
• Development of preeclampsia features 1, 2
• Neurological signs or symptoms (headache, visual changes, hyperreflexia with clonus) 2, 4
• Inability to control BP with ≥3 antihypertensive drug classes 2
• Diastolic BP ≥90 mmHg plus new proteinuria and any symptom 4

Preeclampsia-Specific Management

Magnesium Sulfate for Seizure Prophylaxis

• Administer MgSO₄ for preeclampsia with severe hypertension (≥160/110 mmHg) or with neurological symptoms (headache, visual changes) 1, 2, 4, 3
• Also indicated for eclampsia treatment 4
• Typical dosing: 4 g IV or 10 g IM loading dose, followed by 5 g IM every 4 hours or 1 g/h infusion until delivery and for at least 24 hours postpartum 1

Critical pitfall: One-third of eclamptic seizures occur with diastolic BP ≤100 mmHg, so severe hypertension may be absent 4. Do not wait for severe BP elevation to administer MgSO₄ if neurological symptoms are present.

Inpatient vs. Outpatient Management

• All women with preeclampsia should be assessed in hospital when first diagnosed 1, 3
• Stable patients may subsequently be managed as outpatients if they can reliably report problems and monitor BP 1, 3

Antenatal Corticosteroids

• Administer between 24+0 and 34+0 weeks if delivery is likely within 7 days 2, 4

Plasma Volume Expansion

• Not recommended routinely 1

Timing of Delivery

Gestational Hypertension Without Preeclampsia

• Delivery can be delayed until 39+6 weeks if BP remains controlled, fetal monitoring is reassuring, and preeclampsia has not developed 1, 2, 3
• A large retrospective study suggested 38–39 weeks as optimum, but this requires confirmation in randomized trials 1

Preeclampsia at Term

• Delivery is recommended at ≥37 weeks' gestation 2, 4, 3

Preeclampsia Before Term

• Consider delivery if any of the following develop 3:
  • Repeated episodes of severe hypertension
  • Progressive thrombocytopenia
  • Progressively abnormal renal or liver enzyme tests
  • Pulmonary edema
  • Abnormal neurological features

Lifestyle Measures

• Encourage regular exercise during pregnancy to maintain health, appropriate body weight, and reduce hypertension likelihood 3
• Home BP monitoring is a useful adjunct to clinic visits 1
• Non-drug management is appropriate when systolic BP is 140–149 mmHg or diastolic BP is 90–99 mmHg 6

Prevention Strategies

Aspirin

• Administer aspirin 150 mg/day to women at increased risk for preeclampsia, starting at 12–16 weeks' gestation 3

Calcium Supplementation

• Consider calcium 1.2–2.5 g/day for women at increased risk, especially if dietary intake is likely low (<600 mg/day) 4, 3

Postpartum Management

• Record BP shortly after birth and again within 6 hours 2
• Continue antihypertensive treatment as needed to maintain BP <140/90 mmHg 2
• Women with preeclampsia should be considered at high risk for complications for at least 3 days postpartum and monitored closely 3
• Switch methyldopa to an alternative agent postpartum due to postnatal depression risk 3
• Avoid NSAIDs for postpartum analgesia unless other analgesics are ineffective 3
• Monitor as inpatient or closely at home for 72 hours postpartum 7

Fetal Surveillance

• Assess fetal biometry, amniotic fluid, and umbilical artery Doppler at first diagnosis of preeclampsia 1
• Repeat every 2 weeks if initial assessment is normal; more frequent monitoring if fetal growth restriction is present 1
• Record cord arterial and venous pH for all growth-restricted infants 1
• Histopathologic examination of the placenta is strongly recommended when fetal growth restriction is diagnosed prenatally or at birth 1

Long-Term Cardiovascular Risk

• Women with any hypertensive disorder of pregnancy have significantly increased lifetime cardiovascular risk and require annual medical review lifelong 2, 3
• Initial recommendations include 3:
  • Achieving prepregnancy weight by 12 months postpartum
  • Limiting interpregnancy weight gain
  • Regular BP monitoring
  • Adopting a healthy lifestyle with exercise and optimal body weight
• Obstetric history should become part of cardiovascular risk assessment in women 8

Common Pitfalls to Avoid

• Do not wait for proteinuria to confirm preeclampsia—it is absent in approximately 25% of cases 4
• Do not dismiss headache as benign in a hypertensive pregnant patient—it must be managed as preeclampsia until excluded 4
• Do not delay antihypertensive treatment while awaiting laboratory results—severe hypertension alone warrants immediate therapy 4
• Recognize that gestational hypertension is not benign—at least 25% will progress to preeclampsia 1
• The highest risk of progression occurs when gestational hypertension presents before 34 weeks 1, 4