Key result
Maternal Fontan circulation was associated with significantly greater placental capillary density (537 vs 424 number/mm2) and area of fibrosis (44.3% vs 32.4%) compared to healthy controls, reflecting chronic hypoxia.
Why the study?
Pregnant women with a Fontan circulation have high risks of obstetric complications that may be affected by low placental blood flow and hypoxia, prompting investigation of placental pathology.
Observational (n=16)
No
Absolute Event Rate: 537% vs 424%
p-value: p=0.03
Placentas from women with a Fontan circulation exhibit significant hypoxic changes, growth impairment, and chronic subchorionic hematoma, which likely contribute to poor pregnancy outcomes such as small for gestational age.
May inform counseling for Fontan pregnancies; leaves open whether placental pathology drives obstetric risks.
BACKGROUND: Pregnant women with a Fontan circulation have a high risk of obstetric complications, such as preterm delivery and small for gestational age (SGA), which may be affected by low blood flow to the placenta and hypoxia. This study investigated placental pathology in a Fontan circulation. METHODS AND RESULTS: Eighteen pregnancies in 11 women with a Fontan circulation were reviewed. Pregnancy outcomes showed 9 miscarriages and 9 live births, with 4 preterm deliveries. Five neonates were SGA (<5th percentile). Eight placentas from live births in 7 women were available for the study. Five placentas had low weight placenta for gestational age, and 7 grossly showed a chronic subchorionic hematoma. Histological examination revealed all placentas had some form of histological hypoxic lesions: maternal vascular malperfusion in 7, fetal vascular malperfusion in 1, and other hypoxia-related lesions in 8. Quantitative analyses, including immunohistochemistry (CD31, CD68, and hypoxia inducible factor-1α antibodies) and Masson's trichrome staining, were also performed and compared with 5 control placentas. Capillary density and the area of fibrosis were significantly greater in placentas from women with a Fontan circulation than in control placentas. CONCLUSIONS: Placentas in a Fontan circulation were characterized by a high frequency of low placental weight, chronic subchorionic hematoma, and constant histological hypoxic changes, which could reflect altered maternal cardiac conditions and lead to poor pregnancy outcomes.
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A 2021 study conducted an observational in Fontan circulation in pregnancy (n=16). Maternal Fontan circulation vs. Healthy pregnant women without complications was evaluated on Placental capillary density (number/mm2) (p=0.03). Maternal Fontan circulation was associated with significantly greater placental capillary density (537 vs 424 number/mm2) and area of fibrosis (44.3% vs 32.4%) compared to healthy controls, reflecting chronic hypoxia.
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