Maternal Fontan procedure is a predictor of a small-for-gestational-age neonate: a 10-year retrospective study

Background: Women with single ventricle cardiac physiologic condition who have undergone Fontan procedures are surviving well into reproductive age and historically have been discouraged from pregnancy, despite the paucity of data regarding maternal and neonatal outcomes. Objective: Our primary objective was to investigate, in a large cohort, the maternal and neonatal outcomes of pregnant women who have undergone the Fontan procedure and to understand maternal and neonatal sequelae of their pregnancies. Study Design: This single-center retrospective cohort study involves pregnant women with a Fontan palliation who delivered at UCLA Medical Center over a 10-year period (2007–2017). All pregnancies were evaluated for differences in maternal and neonatal characteristics. Results: We identified 37 distinct pregnancies in 24 women with a Fontan procedure. The physiologic pregnancy-related increase in cardiac output is blunted substantially in Fontan circulation. Third-trimester cardiac index positively correlated to birthweight z-score (R²=0.48; P=.038) but not to small for gestational age (R²=0.13; P=.339). The most common cardiac complications in pregnancies of >24 weeks gestation were sustained arrhythmia (37.5%) and decompensated heart failure (21%). The 37 pregnancies comprised 25 live births (67.6%), 1 fetal death (2.7%), 9 spontaneous abortions (24%), and 2 pregnancy terminations (5.4%). Of the live births, 60% were preterm at an average gestational age of 34.9±3.7 weeks. Newborn infants were delivered via cesarean in 53%, operative vaginal delivery in 28%, and spontaneous vaginal delivery in 20%. Forty percent of neonates were born small (<10th percentile) for gestational age; 44.0% of all neonates were admitted to the neonatal intensive care unit. Conclusion: Women with a single ventricle and Fontan circulation can have a successful pregnancy, although they are at increased risk for arrhythmias and heart failure. The decreased cardiac reserve in these pregnancies blunts the normal increase in maternal cardiac output, which is associated with preterm delivery and small-for-gestational-age neonates. Further studies are needed to determine to what extent the impaired rise in maternal cardiac output reduces uteroplacental perfusion, placental exchange, fetal growth, and onset of parturition.