Pregnancy in Women With Congenital Heart Disease

Introduction

One in 125 newborns is born with congenital heart disease (1). When a woman with a congenital heart defect becomes pregnant, the increased cardiovascular demands of pregnancy may lead to various complications, including cardiac arrhythmias, heart failure, or thromboembolism (2). Studies conducted in the United Kingdom (UK) indicate that heart disease accounts for 22.5% of all maternal deaths, although congenital heart defects represent only a small proportion of these conditions (3).

In clinical practice, specialists from various medical fields are increasingly encountering women with congenital heart disease who are planning pregnancy or are already pregnant. These women often seek information about the potential risks pregnancy may pose to their own health and that of their unborn child.

This article reviews the most important aspects of healthcare for women with congenital heart disease who are planning pregnancy, have successfully conceived, or have given birth (3).

Most Common Congenital Heart Defects

The European Registry on Pregnancy and Cardiac Disease is the largest database established to date containing information on pregnancy outcomes among women with heart disease. According to data from 2012, 66% of all pregnant women with heart disease had been diagnosed with congenital heart disease (4).

One-third of these patients had relatively simple defects, such as atrial or ventricular septal defects, while two-thirds had more complex conditions, including mitral and pulmonary valve abnormalities, aortic coarctation, transposition of the great arteries, and Marfan syndrome.

High-risk conditions, such as single-ventricle circulation, cyanotic heart defects, or congenital cardiomyopathies, account for approximately 2–5% of all congenital heart diseases in the pregnant population.

A smaller study conducted by Canadian researchers found that more than half of pregnant women with congenital heart disease had pathological shunts, repaired tetralogy of Fallot, or aortic coarctation (5).

Maternal mortality among women with congenital heart disease reaches 1%, approximately 100 times higher than the overall maternal mortality rate in developed countries (2).

During pregnancy, systemic vascular resistance decreases, while circulating blood volume and cardiac output increase (6). Similar hemodynamic changes occur during pregnancy in women with congenital heart disease (7).

A large multicenter clinical study involving 2,966 pregnant women, of whom 56% had congenital heart disease, 32% had valvular heart disease, and 7% had cardiomyopathy, found that 2% of pregnant women with heart disease developed cardiac arrhythmias during pregnancy.

The most frequently diagnosed rhythm disturbances were self-terminating tachycardia and frequent premature ventricular contractions. These arrhythmias were generally detected toward the end of the second trimester or during the third trimester (8).

Researchers also observed that approximately 13% of pregnant women with heart disease developed heart failure, usually toward the end of the second trimester, when plasma volume reaches its maximum, or during the peripartum period, immediately before delivery or within the first 48 hours postpartum (9).

Postpartum hemorrhage was reported in 25% of patients with congenital heart disease (10).

A study conducted in the United States involving 50 pregnant women with aortic coarctation demonstrated that up to 30% developed pregnancy-induced hypertension or preeclampsia (11).

Nevertheless, knowledge about the effects of pregnancy on the health of women with congenital heart disease remains limited, as most studies investigating this issue have been retrospective (12–14), and only a small proportion have included sufficiently long follow-up periods.

On the other hand, pregnancy generally does not impair cardiac function in women with congenital heart disease or cause long-term adverse cardiovascular consequences (15, 16).

The risk of miscarriage depends considerably on the specific congenital heart condition. The highest miscarriage risk, reaching 50%, is observed in women with cyanotic heart disease and those with single-ventricle circulation (17–19).

Congenital cardiac abnormalities are more frequently diagnosed in infants born to women with congenital heart disease, with a reported incidence of 3–5% (20, 21).

An analysis conducted at a single UK center found that pregnant women with congenital heart disease experienced higher rates of preterm delivery (12%) and premature rupture of membranes (14%). Furthermore, one-quarter of their newborns were small for gestational age, with birth weights below the 10th percentile, while neonatal mortality reached 4% (22).

Benefits of Preconception Counseling

Experts emphasize the importance of preconception counseling in reducing maternal mortality (3). The benefits of such consultations have been investigated in several scientific studies (4).

Guidelines issued by the European Society of Cardiology and the American Heart Association recommend that women with congenital heart disease who are planning pregnancy receive counseling from appropriately experienced specialists. These consultations should be provided in specialized cardiology and obstetric clinics (23–25).

Access to such consultations may be limited by geographical factors.

For example, in developed Western countries, women with congenital heart disease who are planning pregnancy are typically managed by a multidisciplinary team comprising obstetricians, gynecologists, cardiologists, hematologists, geneticists, anesthesiologists, and other specialists (26).

In less developed regions, primary healthcare teams must provide comprehensive care for these patients.

If a woman with heart disease is considering assisted reproductive procedures or specific fertility treatment, she should receive specialist counseling before the final pregnancy planning strategy is established.

In certain cases, pregnancy may be contraindicated (Table 1), or the reproductive strategy may need to be modified, for example, by transferring a single embryo to avoid multiple pregnancy (24).

In some conditions, such as pulmonary hypertension, pregnancy may pose an unacceptably high risk to the woman's life (23).

During preconception counseling, women frequently ask questions about potential risks to themselves and their future children (27).

If a woman with heart disease does not wish to become pregnant, it is important to discuss the most appropriate contraceptive methods and consider the possibility of pregnancy termination.

When evaluating a woman planning pregnancy, her overall health status should be assessed through clinical examination and imaging studies, such as echocardiography. Pregnancy-related risks should be evaluated, and her current medications should be reviewed (30, 31).

Avoiding medications with teratogenic effects during pregnancy is particularly important (Table 2).

Patients should be provided with all relevant information (Table 3).

According to international registry data, as many as two-thirds of pregnant women with heart disease used cardiovascular medications during pregnancy (Table 2) (32).

Evaluation of Pregnant Women With Congenital Heart Disease

A woman with congenital heart disease who becomes pregnant without having received preconception counseling from a cardiovascular specialist should be urgently referred for specialized investigations, including echocardiography and, if necessary, cardiac magnetic resonance imaging (MRI), to assess cardiac function and morphological abnormalities.

Ideally, this evaluation should be coordinated by a specialist with the necessary knowledge and experience to comprehensively assess the underlying disease and its complications and develop an appropriate management strategy, including planning surgical interventions that may reduce cardiac workload.

Several risk assessment tools are available in clinical practice to estimate the risk of cardiovascular complications during pregnancy. However, their usefulness is limited, as none of these tools simultaneously accounts for both maternal and fetal risks.

The modified World Health Organization (WHO) risk classification is the most commonly used tool in routine clinical practice (Table 4). It helps assess pregnancy-related risks in women with congenital heart disease and supports clinical decision-making.

Pregnancy and New Symptoms: How Should They Be Managed?

Even a normal pregnancy may cause shortness of breath and palpitations. When these symptoms occur in a pregnant woman with congenital heart disease, it is important to respond appropriately and carefully assess her health.

In some cases, a pregnant woman with congenital heart disease may develop a serious cardiovascular complication (Table 5), and the resulting symptoms may be the first manifestations she experiences.

The management of these potentially life-threatening conditions depends on the stage of pregnancy, and patients often need to be referred to a specialized medical center (29).

Justas Simonavičius, MD

Vilnius University Hospital Santaros Klinikos

Prepared according to: Cauldwell M, Dos Santos F, Steer PJ, Swan L, Gatzoulis M, Johnson MR. Pregnancy in women with congenital heart disease. BMJ. 2018 Mar 9;360:k478.

Read more in Internistas, No. 6, 2018.