What is the management and treatment plan for a pregnant woman with gestational hypertension?

Management of Gestational Hypertension

For pregnant women with gestational hypertension, initiate antihypertensive treatment when blood pressure reaches ≥140/90 mmHg, targeting diastolic BP of 85 mmHg and systolic BP between 110-140 mmHg, using methyldopa, labetalol, or long-acting nifedipine as first-line agents. 1, 2, 3

Blood Pressure Thresholds and Treatment Strategy

Non-Severe Hypertension (140-159/90-109 mmHg)

• Begin pharmacological treatment at BP ≥140/90 mmHg with target diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg 1, 2, 3
• First-line medications include methyldopa, labetalol, oxprenolol, and long-acting nifedipine 1, 3
• Metoprolol is an acceptable alternative 3
• For BP 140-149/90-95 mmHg without risk factors, non-pharmacologic management with close supervision and activity limitation is reasonable, though pharmacologic treatment is increasingly preferred 4

Severe Hypertension (≥160/110 mmHg)

• BP ≥160/110 mmHg constitutes a hypertensive emergency requiring immediate treatment within 15 minutes in a monitored setting to prevent maternal stroke 1, 2, 3
• Acceptable urgent treatment agents include:
  • Oral immediate-release nifedipine 1, 2, 3
  • Intravenous labetalol 1, 2, 3
  • Intravenous hydralazine 1, 2, 3
• Avoid intravenous hydralazine as first-line therapy due to association with more perinatal adverse effects compared to other agents 4

Maternal Monitoring Protocol

Initial Assessment

• All women with gestational hypertension should be assessed in hospital when first diagnosed 2
• Perform urinalysis at each visit to detect proteinuria (≥300 mg/L or ≥500 mg/24-hour or dipstick 2+ or more indicates progression to preeclampsia) 4, 1, 2

Ongoing Clinical Evaluation

• Regular assessment for neurological signs including clonus, headache, visual disturbances, and epigastric pain 1, 2
• Laboratory tests including hemoglobin, platelet count, liver enzymes (AST/ALT), uric acid, and creatinine at minimum at 28 and 34 weeks of gestation 1
• More frequent laboratory monitoring if symptoms develop or BP control deteriorates 1

Fetal Monitoring Protocol

• Begin ultrasound assessment of fetal well-being at 26 weeks of gestation 1, 2
• Subsequent evaluations every 2-4 weeks if fetal biometry is normal 1
• Assessments should include fetal biometry, amniotic fluid volume, and umbilical artery Doppler 2
• Increase monitoring frequency to weekly or more if fetal growth restriction is suspected 1, 2

Indications for Immediate Hospitalization

• Development of preeclampsia (proteinuria ≥300 mg/L or ≥500 mg/24-hour) 1, 2
• Severe hypertension (BP ≥160/110 mmHg) 1, 2, 3
• Neurological signs or symptoms (severe headache, visual disturbances, altered mental status) 1, 2
• Laboratory abnormalities suggesting disease progression (thrombocytopenia, elevated liver enzymes, rising creatinine) 1
• Inability to control BP with ≥3 antihypertensive drug classes 3

Delivery Timing

• For gestational hypertension without preeclampsia, delivery can be delayed until 39+6 weeks if BP is controlled with medication, fetal monitoring remains reassuring, and preeclampsia has not developed 1, 2, 3
• Observational data suggests optimal delivery timing between 38-39 weeks, though this requires confirmation with randomized trials 1
• Earlier delivery is indicated if severe hypertension cannot be controlled, preeclampsia develops, or fetal monitoring becomes non-reassuring 1, 2

Medication-Specific Considerations

Methyldopa

• Safe for use throughout pregnancy with extensive clinical experience 4, 3, 5
• May cause false-positive urine tests for catecholamines and pheochromocytoma screening 5
• Can cause darkening of urine when exposed to air (benign metabolite breakdown) 5

Labetalol

• Safe and effective with fewer troublesome side effects than hydralazine 4, 3, 6, 7
• Small amounts (0.004% of maternal dose) excreted in breast milk 6
• May cause false-positive amphetamine screening in urine drug tests 6
• Monitor for bradycardia, hypotension, and hypoglycemia in neonates 6

Nifedipine (Long-Acting)

• Preferred calcium channel blocker for chronic BP control 1, 3, 8
• Avoid grapefruit juice, which increases nifedipine levels by 2-fold 8
• Exercise caution when co-administering with IV magnesium sulfate due to risk of excessive hypotension 8
• Small amounts excreted in breast milk; nursing not recommended 8

Atenolol

• Use with caution or avoid due to association with fetal growth retardation related to duration of treatment 4

Absolutely Contraindicated Medications

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

Prevention Strategies

Low-Dose Aspirin

• Administer 75-162 mg daily from weeks 12-36 of pregnancy in women with history of early-onset preeclampsia (<28 weeks) 4, 2, 3
• Should be started pre-pregnancy or from diagnosis of pregnancy but before 16 weeks gestation 3
• Take at bedtime for optimal effect 3

Calcium Supplementation

• At least 1 gram daily during pregnancy reduces preeclampsia risk by approximately 50%, with greatest effect in high-risk women 3

Interventions NOT Recommended

• Calcium supplementation at 2 g/day has not consistently shown benefits 4
• Fish oil supplementation is not recommended 4
• Weight reduction during pregnancy in obese women is not recommended due to association with reduced neonatal weight 4
• Salt restriction is not advised; maintain normal diet 4

Magnesium Sulfate for Seizure Prophylaxis

• Administer magnesium sulfate to all women with preeclampsia who have proteinuria and severe hypertension, or hypertension with neurological signs/symptoms 2, 3
• Continue during labor and for at least 24 hours postpartum 9
• Magnesium sulfate is not routinely indicated for gestational hypertension without preeclampsia features 9

Postpartum Management

• Monitor BP for at least 6 weeks postpartum, as gestational hypertension typically resolves within 42 days 4, 2
• Women with gestational hypertension have more than doubled lifetime risk of ischemic heart disease 3
• Recommend annual medical review lifelong for cardiovascular risk assessment, including BP monitoring, lifestyle modifications, and metabolic factor control 3

Common Pitfalls to Avoid

• Do not delay treatment waiting for BP to reach 160/110 mmHg—initiate therapy at 140/90 mmHg to prevent progression 1, 2, 3
• Do not use intravenous hydralazine as first-line for acute severe hypertension due to increased perinatal adverse effects 4
• Do not continue pregnancy beyond 39+6 weeks even with good BP control, as risks increase 1, 2
• Do not miss the transition to preeclampsia—check urine protein at every visit 1, 2
• Do not prescribe ACE inhibitors or ARBs under any circumstances during pregnancy 3