Moderate Diagnostic Yield of Exome Sequencing in Fetal Growth Restriction: Retrospective Insights

OBJECTIVE: To determine whether invasive genetic testing should be systematically proposed in cases of FGR. METHODS: Descriptive retrospective study of 159 FGR cases (defined by an estimated fetal growth < 3rd percentile, regardless of Doppler findings) managed at the Toulouse Fetal Medicine Center (TFMC) during 2022-2023. RESULTS: Mean gestational age at diagnosis was 23.7 weeks. Head circumference < 3rd percentile was observed in 35% of cases, hemodynamic signs in 57%, and oligohydramnios in 11%. Invasive testing was performed in 56% (n = 89) of cases, with a diagnostic yield in cases with hemodynamic signs of 19% for genetic syndromes (whether chromosomal or monogenic), which dropped to 11% (n = 8) in isolated FGR. Postnatally, 50% (n = 67) of cases were attributed to placental causes, 31% (n = 41) to genetic disorders (of which 41% had a negative prenatal genetic workup), while 13% remained unexplained. Placental causes were most often due to chronic maternal vascular malperfusion (72%). CONCLUSION: Findings support the systematic offer of exome sequencing in second-trimester FGR, regardless of whether it is isolated, associated with head circumference < 3rd percentile, or with abnormal hemodynamic profiles.