Management of Hypotension in Pregnant Women
The management of hypotension in pregnant women should focus on identifying the cause, ensuring adequate hydration, and positioning the patient in left lateral decubitus position to improve venous return and cardiac output.
Definition and Clinical Significance
- Hypotension during pregnancy is generally defined as blood pressure below 110/65 mmHg, which can compromise uteroplacental perfusion and lead to fetal growth restriction 1
- Maternal hypotension is associated with lower placental perfusion rates and may result in smaller neonates and increased risk of fetal dystrophy 1
Causes of Hypotension in Pregnancy
- Physiologic changes of pregnancy (vasodilation due to hormonal changes) 2
- Position-related (supine hypotensive syndrome from compression of inferior vena cava) 2
- Orthostatic hypotension (more common in pregnancy due to increased blood volume) 2
- Iatrogenic causes (excessive antihypertensive therapy in women with hypertensive disorders) 2
- Regional anesthesia during labor and delivery 2
Assessment of Hypotensive Pregnant Women
- Blood pressure should be measured after the patient sits or lies for 5 minutes, then again at 1 and/or 3 minutes after standing to test for orthostatic hypotension 2
- Ambulatory blood pressure monitoring may provide more accurate assessment of blood pressure patterns, though evidence from randomized trials is lacking 3
- Assess for signs of inadequate organ perfusion: dizziness, syncope, decreased urine output, altered mental status 2
Management Strategies
Non-pharmacological Interventions
- Left lateral decubitus positioning to relieve inferior vena cava compression 2
- Adequate oral hydration to maintain intravascular volume 2
- Compression stockings to improve venous return 2
- Avoidance of rapid position changes 2
- Regular, small meals to prevent postprandial hypotension 2
Pharmacological Management
- Mineralocorticoids (such as 11-Desoxycorticosteronönanthat) have been shown to improve maternal blood pressure and placental perfusion in pathologic hypotension, resulting in better fetal outcomes 1
- Intravenous fluid boluses for acute symptomatic hypotension 2
- Vasopressors may be considered in severe cases but should be used with caution 2
Management in Special Situations
Hypotension During Regional Anesthesia
- Pre-hydration with intravenous fluids before regional anesthesia 2
- Left lateral tilt positioning during cesarean section 2
- Careful titration of anesthetic agents 2
Hypotension in Women on Antihypertensive Therapy
- Antihypertensive drugs should be reduced or ceased if diastolic BP falls below 80 mmHg 2
- Target diastolic BP should be 85 mmHg in office settings (and systolic BP of 110-140 mmHg) 2
- In women with chronic and gestational hypertension, diastolic BP should not be lowered below 80 mmHg 2
Monitoring and Follow-up
- Regular blood pressure monitoring throughout pregnancy 2
- Assessment of fetal growth and well-being with ultrasound if persistent hypotension is present 2
- Monitoring for signs of inadequate placental perfusion 1
Prevention of Adverse Outcomes
- Early identification and treatment of maternal hypotension improves fetal outcomes 1
- Maintaining adequate hydration throughout pregnancy 2
- Avoiding prolonged standing or lying in supine position 2
- Regular prenatal care to monitor maternal and fetal well-being 2
Cautions and Pitfalls
- Overly aggressive treatment of hypertension in pregnancy can lead to maternal hypotension and compromised uteroplacental blood flow 2
- Magnesium sulfate should not be given concomitantly with calcium channel blockers due to risk of hypotension from potential synergism 2
- Orthostatic hypotension should be managed with non-pharmacological approaches first in women with supine hypertension 2