Predictors of spontaneous pregnancy loss in single ventricle physiology

Abstract

Background: Pregnant patients with single ventricle (SV) physiology carry a high risk of spontaneous pregnancy loss (SPL), yet the clinical factors contributing to this risk are not well defined.

Methods: Single-centre retrospective study of pregnant patients with SV physiology seen in cardio-obstetrics clinic over the past 20 years with chart review of their obstetric history. Patients without a known pregnancy outcome were excluded. Univariable Bayesian panel-data random effects logit was used to model the risk of SPL.

Results: The study included 20 patients with 44 pregnancies, 20 live births, 21 SPL and 3 elective abortions. All had Fontan palliation except for two with Waterston and Glenn shunts. 10 (50%) had a single right ventricle (RV). 14 (70%) had moderate or severe atrioventricular valve regurgitation (AVVR). Atrial arrhythmias were present in 16 (80%), Fontan-associated liver disease (FALD) in 15 (75%) and FALD stage 4 in 9 (45%). 12 (60%) were on anticoagulation. Average first-trimester oxygen saturation was 93.8% for live births and 90.8% for SPL. The following factors were associated with higher odds of SPL: RV morphology (OR 1.72 (95% credible interval (CrI) 1.0008-2.70)), moderate or severe AVVR (OR 1.64 (95% CrI 1.003-2.71)) and reduced first-trimester oxygen saturation (OR 1.83 (95% CrI 1.03-2.71) for each per cent decrease in O2 saturation.

Conclusion: Pregnant patients with SV physiology, particularly those with RV morphology, moderate or severe AVVR, and lower first-trimester oxygen saturations, have a higher risk of SPL. Identifying these clinical risk factors can guide preconception counselling by the cardio-obstetrics team.

Keywords: Fontan Procedure; Heart Defects, Congenital; Pregnancy.

Figure 1. Placental pathology specimen with subchorionic haemorrhage. This placenta was small for age, with a stable subchorionic haemorrhage. At pathological examination, a 13 cm subchorionic haematoma was found at the margin, with diffuse choriamniotic hemosiderosis of the membranes and chorionic plate. The image shows numerous brown haemosiderin-laden macrophages in the chorionic plate (100× magnification, H&E stain).