Risks for Pregnant People with Chronic Hypertension without Preeclampsia
Pregnant individuals with chronic hypertension without preeclampsia are at significantly increased risk of delivering small for gestational age babies and preterm birth, with the risk of small for gestational age being 2-3 times higher than in normotensive pregnancies.
Increased Risks Associated with Chronic Hypertension in Pregnancy
Small for Gestational Age (SGA) Babies
- Women with chronic hypertension without superimposed preeclampsia have a 2.9-fold increased risk of delivering small for gestational age babies compared to the general population 1
- This risk remains significant (OR 2.4; 95% CI 2.1-2.9) even after controlling for maternal characteristics such as age, parity, BMI, smoking, and ethnic origin 2
- The risk is independent of whether preeclampsia develops, though superimposed preeclampsia further increases this risk 2
Preterm Birth
- Chronic hypertension is associated with a significant risk of preterm delivery 3
- Approximately 15% of all preterm births are indicated early deliveries related to hypertensive disorders 3
- The risk of preterm delivery increases substantially when blood pressure is poorly controlled, particularly with diastolic blood pressure ≥110 mmHg before 20 weeks gestation 1
Risk of Superimposed Preeclampsia
- Women with chronic hypertension have a 25% risk of developing superimposed preeclampsia 3
- Severe hypertension (diastolic BP ≥110 mmHg) before 20 weeks increases this risk by 5.2-fold 1
- When preeclampsia is superimposed on chronic hypertension, outcomes for both mother and infant are worse than with de novo preeclampsia 3
Other Significant Risks
- Increased risk of fetal growth restriction 3
- Higher risk of placental abruption 3
- Increased risk of congestive heart failure and acute renal failure in the mother 3
- Higher perinatal morbidity, particularly with severe hypertension before 20 weeks 1
Risk Stratification
High-Risk Features
- Severe hypertension (diastolic BP ≥110 mmHg) before 20 weeks is associated with:
- 3.8-fold increased risk of SGA babies
- 7.4-fold increased risk of delivery before 32 weeks
- 5.2-fold increased risk of superimposed preeclampsia 1
Persistent Risk Despite Normal Blood Pressure
- Even when blood pressure is controlled to normal levels before 20 weeks, women with chronic hypertension still have increased risk of adverse perinatal outcomes compared to women without hypertension 4
- Women with chronic hypertension on antihypertensive medications with normal blood pressures before 20 weeks have a 5-fold increased risk of adverse perinatal outcomes 4
Management Implications
Blood Pressure Control
- Treatment should be reinstituted once BP reaches 150-160 mmHg systolic or 100-110 mmHg diastolic 3
- Aggressive treatment of severe chronic hypertension in the first trimester is critical due to high fetal loss rates (up to 50%) 3
- Target blood pressure range should be 140-150/90-100 mmHg 5
Medication Selection
- Methyldopa is preferred based on long-term safety data 3
- Labetalol is increasingly preferred due to reduced side effects 3, 5
- Extended-release nifedipine is another first-line option, particularly when once-daily dosing is preferred for adherence 5
- ACE inhibitors, angiotensin receptor blockers, and direct renin inhibitors are contraindicated in pregnancy 3, 5
Monitoring
- Close surveillance for development of preeclampsia is essential
- Regular monitoring of fetal growth to detect SGA early
- Consider more intensive monitoring for women with severe hypertension before 20 weeks
Long-Term Considerations
- Women with chronic hypertension in pregnancy require lifelong follow-up due to increased cardiovascular risk 3
- Regular follow-up with a general practitioner for BP monitoring and periodic measurement of fasting lipids and blood sugar is recommended 3
- Adoption of healthy lifestyle with maintenance of ideal weight and regular aerobic exercise is important 3
Understanding these risks allows for appropriate counseling, monitoring, and intervention to improve outcomes for both mother and baby in pregnancies complicated by chronic hypertension.