The findings of a 2023 analysis by Sobhani et al. highlight the increasing prevalence of pregnancies among patients with Fontan circulation, a population characterized by significant obstetric risk.¹ The physiological demands of pregnancy exacerbate the unique hemodynamic challenges inherent to Fontan physiology. Individuals with Fontan circulation are modified World Health Organization (mWHO) Maternal Cardiovascular Risk class III, indicating high maternal risk in pregnancy.² Complications such as significant collateral vessels, protein-losing enteropathy, or Fontan-associated liver disease elevate their risk to class IV, where pregnancy is generally contraindicated. While previous reports have primarily been limited to case series and single-center studies, this research provides a larger study with nationwide data on delivery outcomes in this high-risk population.

Data was derived from the 2000 to 2018 Nationwide Inpatient Sample (NIS), focusing on delivery hospitalizations identified through International Classification of Diseases, Ninth Revision, Clinical Modification and International Classification of Diseases, Tenth Revision, Clinical Modification codes. Between 2000 and 2018, a total of 509 deliveries in women with Fontan circulation were identified. The rate of deliveries increased 12-fold from 2.4 per 1 million in 2000 to 30.3 per 1 million in 2018. Women with Fontan circulation experienced significantly higher rates of obstetric complications compared with those without Fontan physiology, including:

• Hypertensive disorders of pregnancy (14% vs. 8%; risk ratio [RR], 1.79; 95% confidence interval [CI], 1.42-2.27)
• Preterm delivery (16% vs. 7%; RR, 2.37; 95% CI, 1.90-2.96)
• Postpartum hemorrhage (13% vs. 3%; RR, 4.28; 95% CI, 3.35-5.45)
• Severe maternal morbidity (9% vs. 1%; RR, 6.09; 95% CI, 4.54-8.17)

This work represents a significant advancement in understanding of one of the most complex palliative surgeries in congenital heart disease and the impact on delivery outcomes. By leveraging national US data, this study provides a quantifiable view of the exponential increase in the number of pregnancies and associated complications among women with Fontan circulation—a population anecdotally known to face significant obstetric risk but previously lacking comprehensive nationwide data.

As survival rates improve, approximately 80% of patients with Fontan circulation are reaching reproductive age, reflected in the observed 12-fold increase in deliveries from 2000 to 2018. Patients with Fontan circulation face a significantly elevated risk of mortality or severe morbidity during pregnancy (mWHO risk class III or IV); however, this is one of the first studies to quantify delivery outcomes using national data. A recent systematic review³ reported a 54% pregnancy loss rate due to early miscarriage, mid-trimester loss, and termination, which is not captured in this study of inpatient hospital deliveries, suggesting that this cohort may represent a lower-risk subset of individuals with Fontan circulation.

The study underscores the critical need for managing pregnancies in individuals with Fontan circulation within an adult congenital heart disease (ACHD) center that offers robust multidisciplinary collaboration. The ideal model is a combined clinic where ACHD cardiologists and maternal-fetal medicine (MFM) specialists see patients together. Additionally, it is important to be at a center with access to pediatric and neonatal subspecialties, including fetal echocardiography, given the 3-8% risk of CHD in the fetus when there is maternal CHD.⁴ There is also an elevated risk of fetal growth restriction and pre-eclampsia, both of which necessitate more frequent antenatal testing and fetal growth monitoring.⁵ Beyond prenatal visits, input from obstetric anesthesia and cardiac intensivists is essential for crafting detailed delivery plans with contingencies for potential complications and candidacy for advanced therapies. Social workers and care coordinators are vital in handling logistics and ensuring the delivery plan's successful implementation. However, significant disparities in ACHD care exist, as nearly half of the US population lives >1 hour from an ACHD specialist. These barriers are amplified during pregnancy where frequent visits are required, making it particularly difficult for those in rural areas or with limited financial resources.^6,7 Strategies such as expanding telehealth, coordinating shared-care models between ACHD and general cardiologists, and increased satellite clinics have been suggested to improve access to care.⁶

Anticoagulation is one of the more challenging clinical decisions when caring for an individual with Fontan circulation during pregnancy. The prothrombotic state during pregnancy, combined with the passive cavopulmonary circuit, predisposes to thrombosis—yet postpartum hemorrhage remains a common complication, with a reported 13% risk compared with 3% in non-Fontan populations. Currently, neither US nor European guidelines provide consensus on routine anticoagulation during pregnancy in individuals with Fontan circulation,^8,9 leaving management reliant on expert opinion and individualized assessment. Recent reviews¹⁰ suggest routine anticoagulation with low–molecular-weight heparin (LMWH) plus aspirin through 36 weeks, with LMWH resuming after delivery for 12 weeks postpartum. Antepartum and postpartum anticoagulation during pregnancy should be considered for all individuals with Fontan circulation. Additionally, low-dose aspirin for prevention or delaying the onset of pre-eclampsia should be strongly considered based on individual risk profiles.^8,9

While this is the first study to quantify intrapartum risk in patients with Fontan circulation using national data, there are limitations to the NIS dataset that are important to consider when integrating these data into counseling. The NIS dataset has limited historical data, making it difficult to comment on the initial mWHO risk class in this cohort or if patients received preconception counseling and optimization prior to pregnancy. Additionally, while the NIS provides general geographic regions, it does not specify if patients were managed at an ACHD center, which likely influences practice patterns and outcomes. There are also no follow-up data, thus the rate of postpartum complications may be higher than observed in this study as the risk for peripartum complications remains elevated up to 6 months after delivery.

The choice to pursue pregnancy in women with congenital heart disease is nuanced, influenced by a range of personal factors—such as individual preferences, family expectations, and cultural or religious beliefs—as well as cardiovascular risk. Ideally, conversations about pregnancy for individuals with complex conditions like Fontan circulation occur preconception and are led by a multidisciplinary team spearheaded by ACHD and MFM. For some, especially the extreme-risk individuals in mWHO risk class IV, this conversation may focus on contraception and alternatives to pregnancy including adoption, gestational carriers, or, if pregnancy occurs, consideration of termination.

In conclusion, this study provides novel data about the cardiovascular risks during delivery that can help guide discussions surrounding childbearing in individuals with Fontan circulation. These discussions are nuanced and challenging but of the utmost importance, as the decision to pursue pregnancy can have widespread implications on a patient's life. This study is another steppingstone forward as the rapidly expanding field of cardio-obstetrics advances from expert opinion to data-supported recommendations and guidelines.

References

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