Background: Placental maternal vascular malperfusion (MVM) is associated with fetal growth restriction (FGR). While FGR increases the risk of cardiovascular disease, the impact of MVM on fetal cardiac structure is understudied. Methods: We utilized a cohort of autopsied stillbirths; 29 with MVM as the cause of death and 21 with a cause of death unrelated to MVM. Fetal and organ weights and heart measurements were standardized by gestational age and compared between MVM and non-MVM stillbirths. Differences in standardized fetal organ and cardiac measures as compared to standardized fetal body weight were calculated to account for body size. Results: MVM stillbirths had smaller organ and heart weights than non-MVM stillbirths; however, after accounting for gestational age, heart weight was the least affected among all organs. In an analysis of organ weights relative to body size, heart weights were 0.31 standard deviations (SD) larger than expected relative to body weight (95% CI: 0.04, 0.57). Right and left ventricle thicknesses and mitral valve circumference were also larger than expected relative to body weight. Conclusion: Stillbirth due to MVM was associated with relative sparing of heart weight and other heart measurements. The significance of these findings in liveborn infants needs further study.

Background: Differences in the shape of the ductus arteriosus (DA), an important vascular shunt between the pulmonary artery and aorta, may reflect fetoplacental blood flow. Our aim was to examine tapering of the DA in a fetal autopsy population and correlate it with placental pathology and cause of death (COD). Methods: This autopsy case control study of stillborn fetuses selected cases (tapered DA) and consecutive age-matched controls (no DA tapering) between January 2017 and January 2022. We abstracted demographic and clinical data from pathology reports. Autopsy data included COD and histologic evidence of fetal hypoxia. Placental pathology included umbilical cord abnormalities, acute and chronic inflammation, fetal vascular malperfusion (FVM), and maternal vascular malperfusion (MVM). Results: We identified 50 cases and 50 controls. Gestational age ranged from 18 to 38 weeks. Maternal and fetal demographic characteristics did not differ significantly between cases and controls. COD related to an umbilical cord accident/FVM was significantly more prevalent in cases vs controls (46% vs 26%, P = .037), and FVM in the placenta, regardless of COD, trended higher in cases than controls. Conclusion: Tapering of the DA is present in stillborn fetuses and associated with COD related to fetal vascular blood flow obstruction.

Background: The pathology of second trimester fetal loss is not well-characterized due to lack of comprehensive autopsy studies. The purpose of this study is to compare autopsy pathology of second trimester and third trimester stillbirth. Methods: In this retrospective cohort study, fetal autopsies performed in-house with complete placental examination were included. From autopsy reports, maternal demographics, gestational age, sex, body and placental weight, congenital anomalies, and cause of death (COD) were obtained. Immediate COD was coded “probable” or “possible” according to Initial Causes of Fetal Death (INCODE). Results: Among 68 second trimester and 54 third trimester fetal autopsies, at least 1 probable COD was identified in 59/68 (87%) second trimester and 44/54 (81%) third trimester cases. 42/68 (62%) second trimester and 28/54 (52%) third trimester fetuses had probable COD secondary to placental pathology. Among placental causes, 29/42 (69%) second trimester and 14/28 (50%) third trimester stillbirths were related to compromised fetal microcirculation with umbilical cord abnormality. Conclusions: Among stillborn first and second trimester fetuses who undergo autopsy, the most prevalent COD is pathologic placental conditions, particularly those associated with umbilical cord obstruction. This study stresses the importance of placenta examination for establishing COD in both second and third trimester fetuses.

Background: Atrioventricular (AV) reentrant tachycardia is a common type of supraventricular tachycardia (SVT) that occurs in the fetus and neonate. Although many tachycardias resolve within several weeks of birth or respond to medical management, disruptions in the cardiac annulus fibrosus and development of additional accessory pathways may lead to refractory dysrhythmia resulting in fetal hydrops and ultimately, fetal death. Objectives: While accessory pathways have been well documented anatomically in adult and childhood tachyarrhythmias, there are no reports of the histology of these pathways in human fetuses with SVT. Research Design, Subjects, Measures: This is a small case series of 2 fetuses with a history of SVT that resulted in fetal hydrops. Results: In both cases, examination of the cardiac conduction system was unremarkable and examination of the atrioventricular junction revealed a focally thinned and/or discontinuous annulus fibrosus with documented direct continuity between the atrial and ventricular myocardium in 1 case. Conclusions: This case series demonstrates that thinning or absence of the annulus fibrosus is a feature seen in fetal SVT, and the development of subsequent aberrant AV connections due to defective formation of the annulus fibrosus suggests a possible cause for these arrhythmias.