Abstract
The 2024 MBRRACE-UK report showed a rise in overall maternal mortality, with deaths from cardiac disease remaining the main indirect cause, barring deaths from COVID-19. Advancing maternal age and a rise in cardiovascular co-morbidities, along with improvements in congenital heart disease management and assisted reproductive technology have all contributed to an increasingly complex maternity population with higher pregnancy risks. Despite improvements in obstetric and cardiac care, health inequalities for women with multiple comorbidities, socio-economic deprivation and those from Black and Asian ethnic groups persist, with these groups being more likely to have poor cardiovascular and pregnancy outcomes. In this review we consider the importance of pre-conception counselling for women with known heart disease, review the physiological changes of pregnancy and explore maternal risk, from a cardiovascular perspective. Importantly, management of women with moderate to severe heart disease during pregnancy should be delivered by the pregnancy heart team, as coined by the European Society of Cardiology in its 2018 guidelines. Individualized care empowers trust and shared decision making, and early access to multidisciplinary care is vital in optimizing maternal and fetal outcomes.
Introduction
Cardiac disease is the most common cause of indirect maternal mortality in the UK after COVID-19 deaths, with a rise in cardiac maternal death rates in 2020–2022 despite steady decreases over the three preceding triennia. The 2024 report from Mothers and Babies, Reducing Risk through Audits and Confidential Enquiries across the United Kingdom (MBRRACE-UK), has shown a concerning significant increase in overall maternal mortality within this period, even when COVID-19 is excluded. Importantly, only 5% of the women who died from indirect causes within the 2024 report were recognized to have a pre-existing cardiac condition. Despite advances in obstetric and cardiac care, the rising prevalence of maternal cardiovascular morbidity reflects a rise in maternal age, maternal comorbidities including hypertension, obesity, diabetes and pre-eclampsia, and more women with repaired congenital heart disease surviving to reproductive age ( Box 1 ).
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Advancing maternal age
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Increasing prevalence of cardiac risk factors such as obesity, hypertension and diabetes
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Improved survival of women with repaired congenital heart disease
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Increased survival of women with chronic medical conditions (e.g. Turner’s syndrome)
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Advances and success of assisted reproductive techniques in infertility.
In recent years, increased risk of maternal mortality for Black (three-fold) and South Asian (two-fold) women has been described, specifically as both populations are at an increased risk of cardiovascular disease. Ethnic inequalities are long-standing and multifactorial, however the FiveXMore campaign has highlighted and encouraged health professionals to challenge prejudices or assumptions based on race. With women living in the most deprived areas having the highest maternal mortality, the risk for these populations is compounded with increasing socio-economic deprivation and consequent impact on their cardiovascular health.
Maternal cardiovascular disease can be considered in three main groups. Firstly, there are women with known, pre-existing heart disease. Here pre-conception risk assessment and counselling is vital to inform shared decision making. By establishing a baseline “fitness for pregnancy” prior to pregnancy, this can help explain the wider health implications of a pregnancy on both mother and baby, especially where cardiac conditions may be exacerbated by the haemodynamic changes of pregnancy. Secondly, there are women who are diagnosed with heart disease for the first time during pregnancy. In this group, pregnancy may unmask previously asymptomatic or subclinical disease potentially associated with symptom onset during pregnancy. Finally, there is cardiovascular disease with direct links to pregnancy itself, the classical examples being pre-eclampsia and peripartum cardiomyopathy.
The sub-speciality field of cardiac obstetrics has evolved rapidly over the past 10–15 years. The 2018 European Society of Cardiology (ESC) guidelines for the management of cardiovascular disease during pregnancy, introduced the concept of the pregnancy heart team. The management of pregnant women with cardiovascular disease requires a highly skilled multidisciplinary group, with expertize in maternal and fetal medicine, cardiology, anaesthetics, and neonatology. Other expertize such as cardiothoracic surgery, genetics, haematology and paediatric cardiology may be called upon for complex patient groups. The updated ESC cardiovascular disease in pregnancy guideline is due to be published in 2025.
Maternal and fetal outcomes are closely linked; care through pregnancy, and postpartum should be individualized to maximize the chances of a successful outcome, with the woman at the centre of all informed decision making. The 2018 ESC guidelines additionally place emphasis on the availability of, and access to care plans or recommendations from the pregnancy heart team at all times.
This article will review the physiological cardiovascular adaptations during pregnancy and consider aspects important to risk assessment and pre-conception counselling. It will take a symptom based approach to conditions that may manifest during pregnancy, and an overview of the safety profile of medications commonly considered in the management of cardiac disease. The detailed management of congenital heart disease (CHD) during pregnancy will not be covered within this review, but our suggested reading list includes several excellent references on this topic.
Cardiovascular physiological adaptations to pregnancy
Pregnancy causes significant haemodynamic, hormonal, immunological and metabolic reprogramming to successfully accommodate the development and delivery of a baby. Often referred to as the “stress test” of life, a thorough appreciation of the maternal cardiovascular adaptation to pregnancy is important to understand and predict its impact on women with heart disease.
The haemodynamic changes of pregnancy begin early at 4–6 weeks of gestation, with an increase in cardiac output, predominantly driven by an increase in stroke volume. Throughout a singleton pregnancy there is an approximate 40% increase in circulating blood volume, a 30% decrease in peripheral vascular resistance and a 1–10% rise in heart rate. Cardiac output increases in total by 30–50% over the duration of pregnancy, with the greatest increase in the second trimester. There is a further 50% rise around the time of labour and delivery due to relief of the uterus on the inferior vena cava, catecholamine response to pain, and autotransfusion of uterine blood back into the maternal circulation. Cardiac output then returns to pre-labour levels within 24–48 hours and to pre-pregnancy values within 2–6 weeks postpartum as blood volume, heart rate and stroke volume normalize. In a twin pregnancy cardiac output is approximately 20% higher than a singleton pregnancy. The maternal physiological adaptations to pregnancy are shown in Table 1 . Cardiac changes generally resolve by 3–6 months postpartum however for some women complete resolution may take up to two years.
| Trimester | Labour and delivery | Physiology | |||
|---|---|---|---|---|---|
| 1st | 2nd | 3rd | |||
| Blood volume | ↑ 10–15% | Up to 50% | ↑ 50% | Increased sodium and water retention Increased red cell mass | |
| Cardiac output | ↑ 5–10% | ↑ >30% | ↑ >40% | ↑ 50% | Increased heart rate and stroke volume Catecholamine release leading to increased contractility |
| Stroke volume | ↑ 5–20% | ↑ >30% | ↑ >30% | ↑ 50% | Increased circulating blood volume |
| Heart rate | ↑ 5–10% | ↑ 10% | ↑ 15% | ↑ | Baroreceptor stimulation due to low afterload |
| Systolic blood pressure | ↔ | ↓ 5% | ↑ 5–10% | ↑ | |
| Systemic vascular resistance | ↓ 5–10% | ↓ 30% | ↓ <5% | Endocrine related vasodilatation Increased nitric oxide production Uterine blood flow | |
Haemodynamic changes in pregnancy causes subtle dilatation of all four cardiac chambers and displacement of the heart due to an enlarging uterus which can be seen in electrocardiogram (ECG) and echocardiogram. The ECG changes in pregnancy are described in Table 2 and examples shown in Figure 1 . The British Society of Echocardiography (BSE) issued a consensus statement in 2023 outlining the normal findings and recommendations for echocardiographic assessment during pregnancy ( Table 3 ).
| ECG parameters | ECG findings in pregnancy | Comments |
|---|---|---|
| Heart rate | Sinus tachycardia: 7–10 bpm increase | From 18 weeks of gestation, 10% will have HR>100 bpm. |
| Cardiac axis (A) | Left axis deviation: Leftward shift in QRS axis | Displacement of the diaphragm by the growing uterus and increased LV size and mass. |
| Cardiac axis (B) | Reversible Right Axis Deviation: Temporary rightward shift in QRS axis | In third trimester, prior to delivery |
| ST segment | Non-Specific ST Segment changes: Mild ST-segment depression | Hormonal fluctuations, increased blood volume |
| T waves | Non-specific T-Wave Changes including T-wave flattening or inversion | Hormonal fluctuations, increased blood volume |
| PR interval | Shortened PR interval (<0.20 seconds) | Increased blood volume, elevated sympathetic tone |
| QRS voltages | Increased QRS amplitude, especially in V5 and V6 | Increased plasma volume, enhanced cardiac output |
| Parameter: echocardiogram | Echocardiogram findings in pregnancy | Comments |
|---|---|---|
| Left ventricular (LV) size | Increased by up to 10–12% | Mild dilation is expected due to increased blood volume and cardiac output. |
| LV ejection fraction (LVEF) | 55–70% | Normal LVEF should be maintained. Although subtle decline from 2 nd trimester to low normal can occur. |
| LV mass | Increased by 30–50% | Eccentric symmetrical hypertrophy as an adaptive response to increased preload and cardiac work. |
| Left atrial (LA) size | Mild enlargement, LA volume ≤34 mL/m 2 | Due to increased circulating blood volume, mild LA enlargement is normal. |
| Right ventricular (RV) size | Mild increase in size | Increased volume load due to higher blood flow. |
| Right ventricular function | TAPSE ≥ 16 mm | Tricuspid annular plane systolic excursion (TAPSE) should remain within normal limits. |
| Pulmonary artery pressure | <35 mmHg | Pulmonary vascular resistance falls during pregnancy therefore estimated pulmonary artery pressures should not be elevated |
| Tricuspid regurgitation (TR) | Mild, physiologic TR may be present | Functional TR is common due chamber enlargement (94% pregnancies), but no structural abnormality. |
| Mitral valve | Mild, physiologic MR may be present | Affect 28% of pregnancies, due to chamber dilatation. |
| Aortic valve | Normal, no regurgitation | No structural abnormalities expected. |
| Pericardial effusion | Small, physiological effusion (≤5 mm) | Affects approximately 40% of pregnancies – more common in 3 rd trimester and if weight gain >12 kg. Usually resolve by 6 weeks postpartum. |
Pregnancy-induced physiological changes increase the risk that women with pre-existing heart disease may develop cardiovascular complications such as heart failure (HF), arrhythmias, and decline in functional status. Data from the Registry of Pregnancy and Cardiac Disease (ROPAC), an international registry of pregnant women from more than 60 countries worldwide, has shown that 13% of women with structural heart disease develop HF in pregnancy, making it the most commonly encountered cardiovascular complication. HF was most common in women with an underlying cardiomyopathy or pulmonary hypertension and associated with pre-eclampsia and adverse maternal and perinatal outcomes. The most vulnerable times for HF are mid-second, and early-third trimester, when the haemodynamic adaptations are at their peak, and around the time of delivery. Postpartum remains a time of increased risk of clinical HF, particularly within the first 4 weeks, as a return to maternal baseline cardiovascular physiology can take 3 months or more to recover.
Pregnancy is also a physiologically hypercoagulable state, with an increased risk of thromboembolic complications. This is of greatest concern in women with pre-existing high risk such as those with a history of arrhythmias, a mechanical heart valve, or a Fontan circulation.
Pregnancy also alters the pharmacokinetics of many drugs used to treat cardiovascular disease due to changes in glomerular filtration rate, liver metabolism and expanded plasma volume. Drug dosages must therefore be carefully considered when prescribing, in addition to an understanding whether medications are safe in both pregnancy and breastfeeding.
Pre-conception counselling for women with known cardiac disease
Pre-conception counselling for women of childbearing age with known cardiac disease is an essential component of lifelong care. Pre-conception counselling encompasses discussions on risk of a pregnancy to the mother and developing fetus, including any risk of fetal inheritance of a maternal heart condition, specific management considerations during pregnancy and an agreed approach to labour and delivery. It is also an opportunity to discuss healthy lifestyle changes, smoking cessation, other co-morbidities and mental health.
Counselling must be individualized and take into consideration not only the physical aspects of health, but also the specific emotional and cultural aspects which may be otherwise neglected. For women at high risk of pregnancy related complications, the importance of pregnancy avoidance and robust contraception requires detailed discussion. Sensitive discussions regarding maternal prognosis, dependent upon the underlying disease, are essential and should include the woman’s partner or support. A written summary of these discussions should then be provided for the patient and their GP, with advice to contact their specialist teams early in pregnancy.
With increasing advances and availability of assisted reproductive technology (ART), it is vital to ensure women are informed to seek pre-conception counselling and assessment from their specialists prior to commencing treatment. Those accessing ART already have an associated increased cardiovascular risk, although the precise mechanisms for this remain under investigation. Additionally, ART is associated with an increased risk of gestational diabetes and hypertensive disorders of pregnancy, both of which confer a lifelong increase in cardiovascular risk. A retrospective study of 34 women with cardiac disease who underwent ART showed that those with higher-risk conditions had higher rates of complications; including intra-abdominal bleeding on anticoagulation post egg collection, endocarditis post egg collection and palpitations. Pre-conception counselling should take into consideration the risks of ART.
Baseline pre-pregnancy risk assessment should include a comprehensive patient history and physical examination. Specifics in the history should include screening for cardiac symptoms such as chest pain, palpitations, breathlessness, syncope, exertional symptoms and an assessment of functional status using the New York Heart Association (NYHA) functional class. A previous cardiac history may include any history of prior cardiovascular events, any previous cardiac surgery or percutaneous procedures. In addition, a drug history including an up to date list of prescribed and over the counter medical therapy, a family history specifically of cardiac disease, and a thorough social history including smoking, alcohol, recreational drug habits, and an understanding of the patient’s social support.
Physical examination should include measurements of bilateral upper limb blood pressure and oxygen saturations. Initial investigations may include a blood and urinary panel including natriuretic peptide levels; 12-lead electrocardiogram (ECG); and comprehensive transthoracic echocardiogram. Additional genetic screening, or genetic counselling may be considered when clinically indicated. Further cardiovascular imaging may also be recommended, for example cardiac magnetic resonance imaging (MRI) in cases of cardiomyopathy, or cardiac computed tomography (CT) or magnetic resonance angiography of the aorta in aortic pathology. A pre-pregnancy exercise test may be helpful in some cases to assess functional capacity and physiological response to exercise.
For pregnant women with cardiac disease whose original lesion was either a congenital heart defect, a cardiomyopathy, aortopathy or other inherited cardiac condition a detailed fetal echocardiogram should be arranged between 18 and 20 weeks’ gestation.
Predicting risk in pregnancy is complex, and an individualized risk assessment should be conducted by a multi-professional team. Risk is dependent upon a number of maternal factors including baseline functional status, ventricular function, the presence of cyanosis or pulmonary hypertension, severity of any valvular pathology, and prior cardiovascular events. Other factors considered to increase pregnancy risk include the need for continuation or initiation of cardiac medication in pregnancy, or the need to withdraw potentially fetotoxic medication, maternal comorbidities such as hypertension, obesity and diabetes. Relevant non-cardiac variables include access to care, ethnicity particularly Black or Asian populations, the use of fertility medication and prior obstetric complications such as pre-eclampsia, intrauterine growth restriction and stillbirth.
Previous studies have shown that B-type natriuretic peptides (BNP) are elevated in pregnant women compared to non-pregnant controls but remain within normal limits. Natriuretic peptides (BNP and NT-pro-BNP) are often measured in women with pre-existing structural heart disease during pregnancy. From a practical perspective NT-pro-BNP and BNP offer greatest utility for their negative predictive value in predicting the likelihood of cardiovascular events during pregnancy. Serum NT-pro-BNP >128 pg/mL at 20 weeks’ gestation has been shown to predict a higher likelihood of cardiovascular events in women with repaired CHD. A BNP <100 pg/ml had a negative predictive value of one hundred percent in identifying events during pregnancy in a cohort of 78 women with heart disease compared to healthy controls.
There are several statistically-derived and one lesion-specific risk classification system currently used to determine the risk of pregnancy in those with cardiac disease. The current ESC guidelines for the management of cardiovascular diseases during pregnancy recommend the use of the Modified World Health Organization (mWHO) classification of maternal risk. This classification is disease specific, where cardiac disease is placed into four groups, mWHO I to IV. Modified WHO I is considered low risk; women with lesions in mWHO IV on the other hand have an extremely high risk of severe maternal morbidity or mortality. Women with mWHO IV risk should be counselled against pregnancy, and if pregnancy occurs, interruption of pregnancy should be discussed ( Table 4 ). Further refinement of risk can be gained through use of the other published risk scores such as the Cardiac Disease in Pregnancy Study (CARPREG II) Risk Index, and the Zwangerschap bij Aangeboren HARtAfwijking (Pregnancy in Women with Congenital Heart Disease), ZAHARA risk score.
