(160) Fetal single ventricle defects are associated with high rates of growth restriction and intrauterine demise

164 cases diagnosed at 20-33 weeks were included (HLHS 118, HRHS 46). FGR occurred in 18% and did not differ between HLH (n=21) and HRH (n=9, p=0.79). The majority (70%) of FGR was early onset and similar in HLH (67%) and HRH (78%). With early-onset FGR, severe FGR was common in both groups (43%) (Table). Among all FGR fetuses, UA Dopplers were normal in the majority (n=21, 70%). There were 9 IUFDs in the cohort (5%, 2 HRH, 7 HLH) of which 3 (33%) occurred in early onset FGR fetuses. 6 IUFDs occurred among 134 normally grown fetuses (4.5%) resulting from hydrops (2 HRH, 1 HLH), spontaneous preterm labor with intrapartum demise (2 HLH (1 polyhydramnios, 1 oligohydramnios)), and severe Doppler abnormalities (1 HLHS).

Conclusion: In single ventricle cardiac defects, early onset FGR and IUFD are common. The cause of early onset FGR is unknown and may not be due to placental insufficiency given majority have normal UA PI values. Aside from hydrops, IUFD is more common when FGR is present. These findings justify increased pregnancy surveillance in this population.