What is the management approach for hypertensive disorder in pregnancy?

Management of Hypertensive Disorders in Pregnancy

All pregnant women with blood pressure ≥140/90 mmHg (or ≥135/85 mmHg at home) should receive antihypertensive treatment 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

Classification and Diagnostic Framework

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

• Chronic hypertension: Present before pregnancy or diagnosed before 20 weeks gestation 1, 2
• Gestational hypertension: New-onset hypertension after 20 weeks without proteinuria; 25% will progress to preeclampsia 2, 3
• Preeclampsia: Gestational hypertension with proteinuria ≥30 mg/mmol (≥0.3 mg/mg) on protein/creatinine ratio 1, 3
• Superimposed preeclampsia: Chronic hypertension with new-onset proteinuria or worsening hypertension after 20 weeks 1, 3

A critical pitfall is misclassifying chronic hypertension as gestational hypertension when BP is first measured after 12 weeks, as the physiologic first-trimester BP decrease may mask underlying chronic disease. 1

Blood Pressure Thresholds and Treatment Initiation

Non-Severe Hypertension

Initiate pharmacological treatment when office BP is consistently ≥140/90 mmHg (or home BP ≥135/85 mmHg) for all hypertensive disorders of pregnancy. 1, 2 This recommendation is based on the CHIPS trial, which demonstrated that treating at this threshold reduces severe hypertension development and associated maternal complications (thrombocytopenia, abnormal liver enzymes, longer hospital stays) without compromising fetal outcomes. 1

• Target diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg 1, 2, 4
• Reduce or cease antihypertensives if diastolic BP falls below 80 mmHg 1
• The approach of waiting until BP reaches 160/110 mmHg before treating is logically inconsistent with the need for urgent treatment at that threshold 1

Severe Hypertension (Hypertensive Emergency)

BP ≥160/110 mmHg requires immediate treatment within 15 minutes in a monitored setting to prevent maternal stroke. 1, 2, 4 This represents a medical emergency with significantly increased cerebrovascular risk. 1

Acceptable agents for acute management include:

• Oral immediate-release nifedipine (first-line option) 1, 2, 4
• Intravenous labetalol 1, 2, 4
• Intravenous hydralazine 1, 2, 3
• Oral labetalol may be used if the above are unavailable 1

First-Line Antihypertensive Medications

The three preferred agents for ongoing BP control are methyldopa, labetalol, and long-acting nifedipine. 1, 2, 4 These medications have established safety profiles in pregnancy with evidence of improved fetal outcomes. 5

Methyldopa

• Safe throughout pregnancy with published reports showing improved fetal outcomes in 332 pregnant hypertensive women 5
• Long-term follow-up of children exposed in utero showed no adverse developmental effects; at age 4, children of treated mothers scored higher on developmental indices than those of untreated mothers 5
• Must be avoided postpartum due to risk of postnatal depression 4

Labetalol

• Effective for both chronic control and acute management 1, 2, 4
• Should not be used concomitantly with calcium channel blockers due to risk of severe hypotension 4

Long-Acting Nifedipine

• Effective for chronic BP control 1, 2, 4
• Immediate-release formulation preferred for acute severe hypertension 2, 4

Second and Third-Line Agents

• Hydralazine and prazosin may be used when first-line agents are insufficient 1, 3

Preeclampsia-Specific Management

Initial Assessment and Monitoring Strategy

Women with preeclampsia should be assessed in hospital when first diagnosed; stable patients may subsequently be managed as outpatients if they can reliably report problems and monitor BP. 1

Maternal monitoring requirements include:

• BP monitoring at least every 4 hours while awake 1
• Repeated proteinuria assessments if not already present 1
• Clinical assessment including clonus 1
• Minimum twice-weekly blood tests: hemoglobin, platelet count, liver function, renal function including uric acid (associated with worse maternal and fetal outcomes) 1

Fetal monitoring includes:

• Initial assessment to confirm fetal well-being 1
• Serial ultrasound surveillance if fetal growth restriction is present 1

Magnesium Sulfate for Seizure Prophylaxis

Women with preeclampsia who have proteinuria and severe hypertension, or hypertension with neurological signs or symptoms, should receive magnesium sulfate for convulsion prophylaxis. 1, 2, 3 The MAGPIE trial demonstrated that magnesium sulfate approximately halves the rate of eclampsia, with approximately 100 women needing treatment to prevent one seizure. 1

• Do not administer magnesium sulfate with calcium channel blockers due to severe hypotension risk 4
• Eclamptic seizures may develop for the first time in the early postpartum period 1

Indications for Delivery in Preeclampsia

Women with preeclampsia should be delivered at 37 weeks and zero days gestation, or earlier if any of the following develop: 1, 2

• Repeated episodes of severe hypertension despite maintenance treatment with 3 classes of antihypertensive agents 1
• Progressive thrombocytopenia 1
• Progressively abnormal renal or liver enzyme tests 1
• Pulmonary edema 1
• Abnormal neurological features (severe intractable headache, repeated visual scotomata, or convulsions) 1, 3
• Nonreassuring fetal status 1

For preeclampsia before 34 weeks, manage conservatively at a center with Maternal-Fetal Medicine expertise unless delivery indications emerge. 1 Administer antenatal corticosteroids between 24+0 and 34+0 weeks if delivery is likely within 7 days. 2

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. 2, 4 This allows for optimal fetal maturation while maintaining maternal safety.

Management includes:

• BP monitoring and antihypertensive therapy to maintain target BP 1, 2
• Laboratory testing for disease progression (twice weekly) 1
• Antenatal testing for fetal well-being 6

Postpartum Management

Early Postpartum Period (First 3 Days)

Women with preeclampsia should be considered at high risk for preeclamptic complications for at least 3 days postpartum. 1

• Monitor BP and clinical condition at least every 4 hours while awake 1
• Continue antihypertensives administered antenatally 1
• Consider treating any hypertension before day 6 postpartum; thereafter, withdraw antihypertensives slowly over days, never abruptly 1
• Avoid NSAIDs for postpartum analgesia unless other analgesics are ineffective, especially with known renal disease, placental abruption, acute kidney injury, or other AKI risk factors (sepsis, postpartum hemorrhage) 1
• Switch from methyldopa to alternative agent due to postnatal depression risk 4

Three-Month Postpartum Review

All women should be reviewed at 3 months postpartum to ensure BP, urinalysis, and laboratory abnormalities have normalized. 1 If proteinuria or hypertension persists, initiate appropriate referral for further investigations. 1

Prevention Strategies

Aspirin for Preeclampsia Prevention

Women at increased risk for preeclampsia should receive 150 mg/day of aspirin starting at 12-16 weeks gestation to prevent preterm (before 37 weeks) but not term preeclampsia. 1, 6 Risk stratification can use a combination of maternal risk factors, BP, placental growth factor (PlGF), and uterine artery Doppler. 1

Calcium Supplementation

Women at increased risk should receive supplemental calcium (1.2-2.5 g/day) if their intake is likely low (<600 mg/day), in addition to aspirin. 1 When intake cannot be assessed, it is reasonable to give calcium. 1

Exercise

Women should exercise during pregnancy to maintain health, appropriate body weight, and reduce the likelihood of hypertension. 1

What NOT to Use

Low molecular weight heparin is not indicated to prevent preeclampsia, even with a history of prior early-onset preeclampsia. 1

Long-Term Cardiovascular Risk

Women with chronic hypertension, gestational hypertension, or preeclampsia have significantly increased lifetime cardiovascular risk and require annual medical review lifelong. 1, 2, 4 This includes increased risk of hypertension, stroke, and metabolic disease later in life. 3, 7

Initial recommendations include:

• Aim to achieve prepregnancy weight by 12 months 1
• Limit interpregnancy weight gain through healthy lifestyle 1
• Regular BP monitoring and control of metabolic factors 3
• Adopt a healthy lifestyle including exercise, eating well, and aiming for ideal body weight 1

Critical Pitfalls to Avoid

• Do not wait until BP reaches 160/110 mmHg to initiate treatment in non-severe hypertension—this increases risk of severe hypertension and maternal complications 1
• Do not use labetalol with calcium channel blockers—risk of severe hypotension 4
• Do not use magnesium sulfate with calcium channel blockers—risk of severe hypotension 4
• Do not continue methyldopa postpartum—risk of postnatal depression 4
• Do not use NSAIDs liberally in preeclampsia—increased AKI risk 1
• Do not assume hypertension will resolve immediately postpartum—BP typically rises over first 5 postpartum days 4
• Do not discharge without long-term follow-up plan—these women need lifelong cardiovascular risk monitoring 1, 2