What is the management and outlook for post-capillary pulmonary hypertension (PH) in pregnancy, according to the World Health Organization (WHO) classification?

Management and Outlook for Post-Capillary Pulmonary Hypertension in Pregnancy According to WHO Classification

Pregnancy is contraindicated in women with post-capillary pulmonary hypertension due to extremely high risk of maternal mortality and severe morbidity (WHO class IV risk). 1

WHO Classification of Maternal Cardiovascular Risk

The WHO classification system stratifies pregnancy risk in women with cardiovascular conditions:

• WHO Class I: No detectable increased risk of maternal mortality and no/mild increase in morbidity
• WHO Class II: Small increased risk of maternal mortality or moderate increase in morbidity
• WHO Class III: Significantly increased risk of maternal mortality or severe morbidity
• WHO Class IV: Extremely high risk of maternal mortality or severe morbidity; pregnancy contraindicated

Pulmonary hypertension, including post-capillary pulmonary hypertension, falls into WHO Class IV, with maternal mortality rates of 25-50% 1.

Maternal Risks

Post-capillary pulmonary hypertension poses severe risks during pregnancy due to:

• Hemodynamic changes during pregnancy (30-50% increase in blood volume, increased cardiac output, heart rate, and stroke volume) 1
• Decreased systemic vascular resistance causing right ventricular overload 1
• High risk of pulmonary hypertensive crises, pulmonary thrombosis, and refractory right heart failure 1
• Highest risk periods: last trimester, delivery, and first months postpartum 1
• Mortality rates of 30-50% in older studies, 17-33% in more recent reports 1, 2

Management Approach for Women Who Become Pregnant

If pregnancy occurs despite contraindication:

1. Early counseling and termination discussion:

   • Termination should be offered and performed in a tertiary center experienced in managing pulmonary hypertension 1
   • If patient chooses to continue pregnancy, inform about high risks (40-100% cardiac event rates) 3

2. Referral to specialized center:

   • Management by multidisciplinary team including pulmonary hypertension specialists, cardiologists, obstetricians, anesthesiologists, and critical care specialists 1, 3

3. Medication management:

   • Continue existing pulmonary hypertension therapy with consideration of teratogenic effects 1
   • Consider prostacyclin therapy (IV or aerosolized) antenatally and peripartum 1
   • Anticoagulation should be maintained during pregnancy if indicated outside pregnancy 1

4. Monitoring and supportive care:

   • Early hospitalization once fetus is viable 1
   • Maintain circulating volume and avoid systemic hypotension, hypoxia, and acidosis 1
   • Provide supplemental oxygen for hypoxemia 1
   • Consider pulmonary artery catheter monitoring during delivery, though risks exist 1

5. Delivery planning:

   • Planned elective delivery with close collaboration between obstetricians and pulmonary hypertension team 1
   • Mode of delivery remains controversial:
     • Epidural anesthesia preferred over general anesthesia for any surgical procedure 1
     • Both vaginal delivery and cesarean section have been successfully managed in case reports 1

6. Critical postpartum care:

   • Highest risk period extends into postpartum phase 3, 2
   • Monitor for volume shifts and increased cardiac filling pressures immediately postpartum 1
   • Consider mechanical support such as extracorporeal membrane oxygenation (ECMO) for circulatory collapse 2

Outlook and Prognosis

Despite advances in pulmonary hypertension treatment, the outlook remains poor:

• Maternal mortality: 25-56% overall 2
• Neonatal survival rates: 87-89% 1
• Recent case series still show maternal mortality of 29% despite advanced therapies 4
• Risk factors for maternal death: late hospitalization, severity of pulmonary hypertension, and general anesthesia 1
• Physiologic changes may cause pulmonary hypertension to worsen during pregnancy and remain worse afterward 1
• Increased incidence of small-for-gestational-age infants and congenital anomalies 1

Prevention for Women with Pulmonary Hypertension

• Effective contraception is essential 1
• Contraceptive considerations:
  • Barrier methods are safe but have unpredictable efficacy 1
  • Progesterone-only preparations (medroxyprogesterone acetate, etonogestrel) are effective 1
  • Levonorgestrel-releasing intrauterine devices are effective but insertion may cause vasovagal reactions 1
  • Combination of two methods may be utilized 1
  • Note that bosentan may reduce oral contraceptive efficacy 1

Despite some reports of successful outcomes in well-managed cases, the high risk of mortality and morbidity means that pregnancy remains strongly contraindicated in women with post-capillary pulmonary hypertension according to WHO classification.