Normal Ejection Fraction During Pregnancy
A normal ejection fraction during pregnancy ranges from 50% to 70%, which is the same as in non-pregnant women. 1
Cardiac Physiological Changes During Pregnancy
- Cardiac output increases by 30-50% during pregnancy due to increased stroke volume and an elevated maternal heart rate (15-20 bpm above pre-pregnancy values) 2, 3
- Heart rate typically increases to 80-95 beats per minute during early second trimester pregnancy 2
- Systemic vascular resistance decreases due to endogenous vasodilators, leading to decreased mean arterial pressure that reaches its lowest point in the second trimester 2, 3
- Despite these significant hemodynamic changes, the normal range for ejection fraction remains 50-70% during pregnancy 1, 4
Clinical Significance of Ejection Fraction During Pregnancy
- An ejection fraction below 40% is considered reduced and represents a predictor of maternal cardiovascular events during pregnancy 1
- Women with ejection fraction <40% should be counseled against pregnancy due to increased risk of complications 1
- Studies show that women who develop peripartum cardiomyopathy maintain normal ejection fraction during gestation before the disease manifests, with PPCM defined as heart failure with ejection fraction <45% 5, 6
- More sensitive measures like global longitudinal strain and global circumferential strain may detect early cardiac dysfunction before ejection fraction changes become apparent 6
Risk Assessment Based on Ejection Fraction
- The CARPREG risk score identifies reduced systemic ventricular systolic function (ejection fraction <40%) as a predictor of maternal cardiovascular events 1
- According to the modified WHO risk classification, important ventricular dysfunction (EF <40%) places women in a high-risk category for pregnancy complications 1
- Women with ejection fraction ≤30% have significantly worse fetal and neonatal outcomes compared to those with ejection fraction >30%, with lower rates of live births (59% vs 90%) 7
Monitoring Recommendations
- Women with normal ejection fraction (50-70%) generally require standard prenatal cardiac monitoring 1, 4
- Those with borderline or mildly reduced ejection fraction (40-49%) require more frequent monitoring during pregnancy 1
- Women with ejection fraction <40% should have frequent echocardiographic surveillance (every 4-8 weeks) to assess for deterioration in cardiac function 1
- Position changes can significantly affect cardiac measurements - the left lateral position is preferred over the supine position, especially after 20 weeks gestation 2, 3
Common Pitfalls in Assessment
- Ejection fraction measurements can vary between imaging modalities and methods (visual vs. quantitative) 1
- When reported as a numerical value, the imaging modality and method of analysis should be specified 1
- Heart failure with preserved ejection fraction (HFpEF) is increasingly recognized during pregnancy and may be missed if focusing solely on ejection fraction 8
- Strain imaging may detect subclinical dysfunction in women with normal ejection fraction who later develop peripartum cardiomyopathy 6