What are the management options for a pregnant woman with hypotension (blood pressure less than 90 mmHg)?

Management of Hypotension (BP <90 mmHg) in Pregnancy

A pregnant woman with systolic blood pressure less than 90 mmHg requires immediate evaluation for the underlying cause, as hypotension in pregnancy—while sometimes physiological—can indicate serious maternal conditions (hemorrhage, sepsis, cardiac dysfunction) or impaired uteroplacental perfusion that threatens fetal well-being.

Understanding Blood Pressure Changes in Pregnancy

The provided guidelines focus exclusively on hypertension management, not hypotension, because hypotension is not a primary hypertensive disorder of pregnancy 1. However, the guidelines do acknowledge that:

• Physiological BP decreases occur in early pregnancy, with blood pressure naturally falling in the first trimester due to decreased systemic vascular resistance 1
• Excessive BP lowering can harm the fetus: Guidelines explicitly warn that lowering blood pressure too aggressively "may impair uteroplacental perfusion and thereby jeopardize fetal development" 1
• Diastolic BP should not fall below 80 mmHg during treatment of hypertension in pregnancy 1, 2

Immediate Assessment Required

When encountering a pregnant woman with systolic BP <90 mmHg, you must rapidly determine:

Pathological Causes (Require Urgent Intervention)

• Hemorrhage: Antepartum bleeding, placental abruption, ruptured ectopic pregnancy
• Sepsis: Chorioamnionitis, pyelonephritis, other infections
• Cardiac dysfunction: Peripartum cardiomyopathy, myocardial infarction, arrhythmia
• Anaphylaxis: Drug reactions, allergic responses
• Iatrogenic: Excessive antihypertensive medication (particularly if diastolic BP <80 mmHg) 2
• Supine hypotensive syndrome: Compression of inferior vena cava by gravid uterus in late pregnancy

Physiological Causes (May Be Normal)

• First/second trimester physiological decrease: Normal pregnancy adaptation 1
• Positional changes: Standing quickly, prolonged standing
• Dehydration: Hyperemesis gravidarum, inadequate fluid intake

Management Algorithm

Step 1: Assess Maternal Stability

• Check for symptoms: dizziness, syncope, altered mental status, chest pain, shortness of breath
• Evaluate for signs of shock: tachycardia, cool extremities, delayed capillary refill, oliguria
• If maternal early warning criteria are met (heart rate >130 or <50 bpm, oxygen saturation <95%, altered mental status, oliguria), this constitutes an emergency requiring immediate hospitalization 3

Step 2: Position the Patient

• Place in left lateral decubitus position to relieve aortocaval compression, which is recommended for pregnant women with blood pressure concerns 1
• Elevate legs if tolerated

Step 3: Identify and Treat Underlying Cause

• If hemorrhage: Activate massive transfusion protocol, obstetric consultation for delivery consideration
• If sepsis: Broad-spectrum antibiotics, fluid resuscitation, source control
• If cardiac: ECG, echocardiography, cardiology consultation
• If medication-related: Hold antihypertensive agents immediately if diastolic BP <80 mmHg 2

Step 4: Fluid Management

• Administer IV crystalloid bolus (500-1000 mL) if no contraindications
• Avoid excessive fluid in pre-eclampsia context, as salt restriction and aggressive fluid administration can be harmful 1
• Monitor for pulmonary edema, especially if any history of hypertensive disorders

Step 5: Fetal Monitoring

• Continuous fetal heart rate monitoring if viable gestational age
• Assess for signs of fetal distress from uteroplacental hypoperfusion
• Delivery may be indicated if fetal distress is present 3

Critical Pitfalls to Avoid

• Do not assume hypotension is always benign: While physiological decreases occur in early pregnancy 1, symptomatic hypotension or systolic BP <90 mmHg warrants investigation
• Do not restrict salt intake: Normal diet without salt restriction is advised in pregnancy, as salt restriction may induce low intravascular volume 1
• Do not overlook medication review: If the patient is on antihypertensive therapy, excessive BP lowering can compromise uteroplacental perfusion 1
• Do not forget positional maneuvers: Left lateral positioning and bed rest in this position are specifically recommended for pregnant women with BP abnormalities 1

Special Considerations

If Patient is on Antihypertensive Therapy

• Reduce or cease antihypertensive therapy if diastolic BP falls below 80 mmHg 2
• The goal of treating hypertension in pregnancy is to maintain BP below 140/90 mmHg but not below 80 mmHg diastolic 1
• Overly aggressive BP reduction can impair uteroplacental perfusion 2

Monitoring Requirements

• Serial BP measurements every 15-30 minutes until stable
• Continuous fetal monitoring if gestational age ≥24 weeks
• Urine output monitoring (oliguria is a maternal early warning sign) 3
• Laboratory evaluation: CBC, metabolic panel, lactate if shock suspected

When to Hospitalize

• Symptomatic hypotension (dizziness, syncope, altered mental status)
• Systolic BP <90 mmHg with any maternal early warning criteria 3
• Evidence of end-organ hypoperfusion (oliguria, altered mental status)
• Fetal distress or concern for uteroplacental insufficiency
• Inability to identify and correct underlying cause in outpatient setting