Placental weight in pregnancies complicated by fetal congenital heart defects

INTRODUCTION: Congenital heart defects (CHD) are the most common malformations. Fetuses with CHD are at an increased risk of being born small for gestational age (SGA), suggesting an impaired placental function. Our aim was to investigate the interdependence between fetal heart and placenta in pregnancies affected by isolated CHD. METHODS: This was a retrospective cohort study at a tertiary referral center. All singleton pregnancies with suspected fetal CHD between 2009 and 2020 were included. Confirmed CHD were allocated to one of six subgroups according to neonatal echocardiography or autopsy. Birth weight (b), placental weight (p), b/p ratio were calculated and compared between the subgroups, respectively. RESULTS: 302 fetuses with confirmed CHD were analyzed. The overall incidence of SGA neonates with isolated CHD was 33/161 (20.4 %), while 28.4 % (38/134) of CHD placental weights were below the 10th percentile, with the highest incidence in cases with isolated univentricular (42.9 %) and left-sided (37.1 %) cardiac lesions. Mean b/p ratio in isolated cases was 5.32 (SD ± 1.51), and 23/134 (17.2 %) were > 90th percentile. 11/302 (3.6 %) of pregnancies were affected by preeclampsia. All neonates were SGA and 7/10 (70 %) placental weights were < 10th percentile. CONCLUSION: The incidence of small placentas, SGA and preeclampsia is increased in pregnancies with fetal CHD. Disturbances in fetal cardio-placental hemodynamics may alter the development of the villous tree resulting in small placentas and fetuses, suggesting a second hit on the placenta, particularly in preeclampsia. Pregnancies with fetal CHD should be followed more closely for placental dysfunction and impaired fetal growth.