What is the management and treatment for a pregnant patient with pregnancy-induced hypertension?

Management of Pregnancy-Induced Hypertension

For pregnant women with pregnancy-induced hypertension, initiate antihypertensive treatment when blood pressure reaches ≥140/90 mmHg, 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

Blood Pressure Thresholds and Treatment Initiation

• Start pharmacological treatment at BP ≥140/90 mmHg in women with gestational hypertension (new-onset hypertension after 20 weeks), pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage or symptoms. 3, 1, 2

• For women with chronic hypertension without these specific features, treatment begins at BP ≥150/95 mmHg. 3, 2

• Non-pharmacological management alone is appropriate for BP 140-150/90-99 mmHg without concerning features, including close supervision, limitation of activities, bed rest in left lateral position, normal diet without salt restriction, and calcium supplementation of at least 1 g daily. 3, 2

Urgent Management of Severe Hypertension

• BP ≥160/110 mmHg constitutes a hypertensive emergency requiring immediate treatment within 15 minutes in a monitored setting to prevent maternal stroke. 3, 1, 2

• First-line agents for acute severe hypertension include:

  • Oral immediate-release nifedipine 3, 1, 2
  • Intravenous labetalol 3, 1, 2
  • Intravenous hydralazine 3, 1

• Position the patient in left lateral decubitus to relieve inferior vena cava compression and improve venous return. 4

First-Line Antihypertensive Medications for Chronic Control

• Methyldopa, labetalol, and long-acting nifedipine are the three preferred agents for ongoing BP control during pregnancy, with methyldopa having the longest safety data including 7.5-year infant follow-up. 3, 1, 2

• Metoprolol is also recommended as an alternative. 3

• Reduce or cease antihypertensive drugs if diastolic BP falls below 80 mmHg to avoid compromising uteroplacental perfusion. 3

Absolutely Contraindicated Medications

• ACE inhibitors, angiotensin receptor blockers (ARBs), and direct renin inhibitors are strictly contraindicated due to severe fetotoxicity, particularly in the second and third trimesters. 3, 2, 5

• If taken inadvertently during the first trimester, switch immediately to another medication and perform close monitoring including fetal ultrasound. 3

Critical Drug Interaction Warning

• Do not administer magnesium sulfate concomitantly with calcium channel blockers due to risk of severe hypotension. 4, 2

• Do not use labetalol concomitantly with calcium channel blockers for the same reason. 2

Indications for Hospitalization

Admit immediately for:

• BP ≥160/110 mmHg (severe hypertension) 3, 1, 2
• Development of preeclampsia features (proteinuria ≥0.3 g/day) 3
• Neurological signs or symptoms (severe headache, visual disturbances, clonus) 3, 1, 2
• Inability to control BP with ≥3 antihypertensive drug classes 1, 2

Preeclampsia-Specific Management

• All women with preeclampsia should be assessed in hospital when first diagnosed; some may be managed as outpatients once stable if they can reliably report problems and monitor their BP. 3

• Administer magnesium sulfate for seizure prophylaxis in women with preeclampsia who have proteinuria and severe hypertension, or hypertension with neurological signs or symptoms. 3, 1, 2

• In low-resource settings, all women with preeclampsia should receive MgSO4: loading dose of 4 g IV or 10 g IM, followed by 5 g IM every 4 hours or 1 g/h infusion until delivery and for at least 24 hours postpartum. 3

• Plasma volume expansion is not recommended routinely in women with preeclampsia. 3

Maternal Monitoring Protocol

For women with preeclampsia, perform:

• BP monitoring continuously or at least 4 times daily 3, 6
• Repeated assessments for proteinuria if not already present 3
• Clinical assessment including clonus 3
• Blood tests at least twice weekly (and with any clinical status change) for hemoglobin, platelet count, liver transaminases, creatinine, and uric acid 3
• Weekly creatinine clearance determination 6
• Weight and urine protein 3 times weekly 6

Fetal Monitoring Protocol

Fetal monitoring should include:

• Assessment of fetal biometry, amniotic fluid, and umbilical artery Doppler ultrasound at first diagnosis 3
• Repeat at 2-week intervals if initial assessment was normal 3
• More frequent amniotic fluid and Doppler assessments in the presence of fetal growth restriction 3
• Serial sonography to monitor fetal growth 6

Timing of Delivery

• For 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

• For preeclampsia at term (≥37 weeks): recommend delivery. 1

• Deliver earlier if: rapid weight gain, decreasing creatinine clearance, appearance of significant proteinuria, suspected fetal growth retardation, or development of severe headache or visual disturbances. 6

• Administer antenatal corticosteroids between 24+0 and 34+0 weeks if delivery is likely within 7 days. 1

Important Clinical Pitfalls

• Do not attempt to diagnose "mild versus severe" preeclampsia clinically as all cases may become emergencies, often rapidly. 3

• At least 25% of women with gestational hypertension will progress to preeclampsia, with highest risk among those presenting before 34 weeks. 3, 1

• Salt restriction may induce low intravascular volume and should be avoided, particularly close to delivery. 3

• Weight reduction is not recommended during pregnancy in obese women as it can lead to reduced neonatal weight and slower subsequent growth. 3

Prevention Strategies

• Low-dose aspirin (75-100 mg/day) should be administered at bedtime in women with a history of early-onset (<28 weeks) preeclampsia, starting pre-pregnancy or from diagnosis of pregnancy but before 16 weeks gestation, and continued until delivery. 3

• Calcium supplementation of at least 1 g daily during pregnancy almost halved the risk of preeclampsia, with greatest effect in high-risk women, though evidence is conflicting. 3

• Fish oil supplementation and vitamin/nutrient supplements have no role in prevention. 3

Postpartum Management

• Record BP shortly after birth and again within 6 hours, continuing antihypertensive treatment as needed to maintain BP <140/90 mmHg. 1

• Switch from methyldopa to an alternative agent postpartum due to risk of postnatal depression. 2

• BP typically rises over the first 5 postpartum days; women may become hypertensive again after initial normalization. 2

Long-Term Cardiovascular Risk

• Women with gestational hypertension or preeclampsia have significantly increased lifetime cardiovascular risk, with relative risk of ischemic heart disease more than doubled. 1, 2

• Women with early-onset preeclampsia, stillbirth, or fetal growth retardation are at highest risk. 2

• Recommend annual medical review lifelong for cardiovascular risk assessment, lifestyle modifications, regular blood pressure control, and control of metabolic factors. 1, 2

• Earlier onset in the first pregnancy correlates with greater recurrence risk in subsequent pregnancies. 2