Congenital heart disease (CHD) refers to malformations of the heart or great vessels that occur during the intrauterine period [1,2]. CHDs represent the most common group of congenital anomalies, and they are observed in approximately 8 to 12 out of every 1000 live births [3,4]. Critical CHD refers to heart conditions that require medical intervention or surgical procedures in the early stages of life. These critical forms account for approximately 20–25% of all CHDs, corresponding to about one in every 500 births [1,5]. In recent years, advances in neonatal cardiac catheterizations, palliative and corrective surgeries, anesthesia techniques, and improvements in intensive care unit conditions have contributed to better outcomes for critical CHDs [6,7].

The increasing use of fetal echocardiography in clinical practice has enabled the prenatal diagnosis of many congenital heart diseases (CHDs), and this allows for the planning of delivery in cases where newborns are anticipated to require urgent medical intervention or treatment. Clinical guidelines on CHDs recommend performing fetal echocardiography between the 18th and 22nd weeks of gestation in pregnancies considered high-risk due to fetal, maternal, or familial factors [8]. Prenatal diagnosis provides valuable time for healthcare professionals and families, enabling a more informed management of the disease [9]. In particular, for patients with ductus-dependent critical CHDs, early detection through screening, before rapid clinical deterioration and the onset of symptoms, plays a vital role in initiating timely treatment [10]. This study aims to evaluate the independent effect of prenatal diagnosis on mortality and clinical outcomes after adjusting for disease severity.

Among the 160 patients with critical CHD included in the study, 52 had a prenatal diagnosis, while 108 did not. When comparing the demographic and clinical characteristics of patients with and without a prenatal diagnosis, statistically significant differences were found between the groups in terms of sex, mean day of postnatal diagnosis, and clinical outcome (p = 0.026, p = 0.004, and p < 0.001, respectively) (Table 1). However, in the multivariate logistic regression analysis performed, it was seen that prenatal diagnosis, presence of any of the following: HLHS, PA, or aortic arch anomalies, and birth weight were found to have a significant effect on mortality rate; however, Aristotle score, gestational age, and the presence of shock symptoms at the time of initial diagnosis had no effect on mortality rate (Table 2).

In this study, an analysis of the prenatal diagnoses revealed that the most common conditions were HLHS in 18 patients (34.6%), pulmonary atresia in 13 patients (25.0%), and transposition of the great arteries (TGA) in 8 patients (15.4%) (Table 3).

In this study, an analysis of postnatal diagnoses revealed that the three most common conditions were TGA in 55 patients (51.1%), HLHS in 18 patients (16.6%), and pulmonary atresia in 12 patients (11.1%) (Table 3).

When the treatments administered to patients with and without a prenatal diagnosis were compared, it was observed that arterial switch operation (ASO) and Tetralogy of Fallot repair were more frequently performed in the group without a prenatal diagnosis. A statistically significant difference was found between the groups in terms of ASO (p < 0.001), whereas no statistically significant difference was observed for Tetralogy of Fallot repair (p = 0.169). On the other hand, Norwood stage 1 operation, modified Blalock–Taussig shunt (MBT) shunt procedure, and aortic arch repair were more frequently performed in the group with a prenatal diagnosis, and statistically significant differences were found between the groups for these procedures (p = 0.002, p < 0.001, and p = 0.001, respectively) (Table 4).

No statistically significant differences were found between the groups with and without a prenatal diagnosis in terms of vital signs (p > 0.05) (Table 5).

In our study, both the VIS and Aristotle score were found to be higher in the group without a prenatal diagnosis; however, no statistically significant association was observed between these parameters and prenatal diagnosis (Table 5).

In this study, complications related to the treatments administered were examined, and it was found that 4 patients had arrhythmia (25%), 4 had sepsis (25%), 2 had atelectasis (12.5%), 2 had multiple organ failure (12.5%), 2 had gastrointestinal perforation (12.5%), 1 had acute renal failure (6.25%), and 1 had sternal dehiscence (6.25%).

When the biochemical parameters of patients with and without a prenatal diagnosis were compared, the mean aspartate transferase (AST) and lactate dehydrogenase (LDH) levels were found to be statistically higher in patients with a postnatal diagnosis, whereas the mean phosphorus level was statistically higher in those with a prenatal diagnosis (Table 6).

In our study, among the group of patients diagnosed with conditions associated with high complexity and mortality, namely HLHS, PA, and aortic arch anomalies, mortality was found to be significantly lower in those with a prenatal diagnosis (p = 0.018) (Table 7).

CHD represents the most common group of congenital anomalies in the neonatal period, encompassing a wide spectrum ranging from mild cardiac defects to critical CHD that require rapid diagnosis and intervention for the newborn’s survival [10,11]. Prenatal diagnosis of CHD is considered beneficial as it enables the identification of critical cardiac defects before birth. This, in turn, allows for parental counseling and the planning of delivery at a specialized cardiac center where immediate postnatal treatment can be initiated [12]. In our study, it was observed that the diagnosis of critical CHD that was not diagnosed prenatally was delayed until the late neonatal period.

Some studies have reported that more adverse outcomes are observed in prenatally diagnosed CHDs [13,14]. This finding may be explained by the fact that more critical types of CHD are more easily detected during ultrasound screening. These findings suggest that survival may no longer be the most important outcome, or prenatal diagnosis may not be the most appropriate criterion for measuring the impact on CHD, particularly in settings with easy access to specialized healthcare. In our study, we consider that the higher mortality rate in the prenatally diagnosed group, in the evaluation where all cases were included, is due to the presence of more critical diseases in this group, the exclusion of patients who died without postnatal diagnosis, the ease and speed of access to health care, and the heterogeneity of the distribution of diagnoses and procedures among the groups. In fact, in our study, it was determined that surgical interventions such as the Norwood operation, aortic arch repair, and Blalock-Taussig shunt, which have high mortality rates, were performed more often in the prenatally diagnosed group.

TGA is one of the most common critical CHD in the neonatal period, and the rate of prenatal diagnosis is increasing. TGA is currently one of the most commonly misdiagnosed CHD in utero. Due to the lack of prenatal diagnosis, patients are often born outside tertiary cardiac centers and cannot be adequately monitored after birth to ensure timely surgical treatment; this may lead to potentially preventable mortality or multi-organ damage [15]. UK national cardiac surgery surveillance data show that prenatal detection for infants with TGA undergoing ASO has increased from 50% before 2016 to over 80% in recent years [16]. Particularly in recent years, survival rates after ASO applied in TGA patients have been reported to be above 97% [17]. In our study, TGA, which has a low postnatal mortality rate, constituted more than half of the patients diagnosed postnatally. In contrast, while the TGA rate was low in patients diagnosed prenatally, HLHS, which has high postnatal mortality, was the most common cardiac pathology. This situation may be related to the high overall mortality rate in patients diagnosed prenatally.

The impact of prenatal diagnosis on survival varies depending on the type of cardiac defect. It is suggested that prenatal diagnosis may allow for the prompt initiation of treatment in order to maintain ductal patency in the newborn, thereby preventing metabolic acidosis, hypoxemia, and organ damage, and ultimately reducing mortality and morbidity. Several case series have reported that this approach has lowered mortality rates in patients diagnosed with HLHS, TGA, and aortic coarctation [18,19]. In conditions such as TGA or HLHS, early intervention is essential to prevent cardiac or neurological damage resulting from hypoxia and adverse hemodynamics. Although these patients often present with more severe lesions compared to those diagnosed postnatally, prenatal diagnosis has been associated with a reduced need for mechanical ventilation, antibiotic therapy, and emergency surgical intervention [20]. In support of this, although overall mortality was found to be higher among patients with a prenatal diagnosis in our study, a significantly lower mortality rate was observed in the subgroup of patients diagnosed with HLHS, PA, and aortic arch anomalies, conditions associated with high complexity and mortality. This finding suggests that prenatal diagnosis in these three critical CHD groups may significantly reduce postnatal mortality.

Studies have reported that the need for cardiopulmonary resuscitation (CPR) at birth is associated with increased mortality [21,22]. In our study, although the difference was not statistically significant (p = 0.153), the need for CPR was higher in the group without a prenatal diagnosis (37%) compared to those with a prenatal diagnosis (25%). Additionally, the significantly higher AST and LDH levels and the significantly later timing of diagnosis in patients without a prenatal diagnosis suggest that these patients may have been diagnosed under poorer clinical conditions. This indicates that patients without a prenatal diagnosis may be more prone to conditions such as acidosis and multiple organ failure, which are known to increase mortality and morbidity.

VIS is a tool used to evaluate cardiovascular pharmacological support. It is calculated as the weighted sum of all administered vasoactive and inotropic agents [23]. Studies have identified the maximum VIS value reached within the first 24 h after surgery as an independent predictor of postoperative mortality and morbidity [23,24]. The Aristotle scoring system, on the other hand, was developed in 1999 under the leadership of Lacour-Gayet with the participation of 50 cardiac surgeons from 23 countries. Its first version, the Aristotle Basic Complexity Score (ABS), is based on three main factors: risk of death, potential for complications, and anticipated technical difficulty. Accordingly, cases are scored between 1.5 and 15 in the ABS system [25]. In our study, no statistically significant difference was found between patients with and without a prenatal diagnosis in terms of VIS and ABS.

The primary limitations of this study include its retrospective design, which is inherently subject to bias. Prenatal follow-up was conducted at centers with varying standards of care, and limited accessibility to prenatal data precluded its inclusion in the analysis. The distribution of diagnoses was not homogeneous between groups, which may affect comparability. Patients who died before a diagnosis could be established or prior to referral to our unit were excluded. The exclusion of patients who terminated their pregnancies and those who died intrauterine may also affect mortality statistics. The higher proportion of males in the prenatally diagnosed group may reflect known sex differences in CHD presentation, but its effect on mortality is likely minimal, as sex was not an independent predictor in regression. Confounding by disease severity cannot be ruled out. As a single-center study, the generalizability of our findings is limited. Small subgroup sizes reduced statistical power, and the regression model has inherent constraints. Finally, long-term outcomes were not available.

In this retrospective cohort, overall mortality was significantly higher among patients with a prenatal diagnosis of critical CHD. This finding is largely explained by the overrepresentation of high-complexity lesions (e.g., HLHS, PA, and aortic arch anomalies) in the prenatally diagnosed group. However, within that specific high-risk subgroup, prenatal diagnosis was associated with a significantly lower mortality rate, suggesting a genuine survival benefit. Prenatal diagnosis may improve outcomes in selected high-risk CHD subgroups, but its overall impact on mortality is confounded by disease severity, case mix, and exclusion of deaths before diagnosis. Therefore, multicenter, prospective studies with longer follow-up and larger, more homogeneous patient populations are needed.