Non-immune fetal hydrops: etiology and outcomes according to gestational age at diagnosis.

OBJECTIVES: Fetal hydrops is associated with increased perinatal mortality and morbidity. The etiology and outcomes of fetal hydrops may differ according to the gestational age (GA) at diagnosis. The aim of this study was to evaluate the causes, evolution and outcomes of non-immune fetal hydrops (NIFH) according to the GA at diagnosis. METHODS: This was a retrospective cohort study of all singleton pregnancies complicated by NIFH at the Fetal Medicine Unit at St George's University Hospital, London between 2000 and 2018. All fetuses had a detailed anomaly and cardiac ultrasound scans, karyotyping and infection screening. Prenatal diagnostic and therapeutic interventions, GA at diagnosis and delivery, as well as pregnancy outcomes were recorded. Regression analysis was used to test for potential association between possible risk factors and perinatal mortality. RESULTS: We included 273 fetuses with NIFH. Etiologies varied significantly in the three trimesters. Excluding women declining invasive testing (n=30), the cause of NIFH was defined as "unknown" in 62 out of 243 cases (25.5%). Chromosomal aneuploidy was the commonest cause in the first trimester. It continued to be a significant etiologic factor in the second trimester along with congenital infections. In the third trimester, the most common etiology was cardiovascular abnormalities. Among the 152 (55.7%) women continuing the pregnancy, 48 (31.6%) had fetal intervention, including the insertion of pleuro-amniotic shunts, fetal blood transfusion and thoracocentesis. Fetal intervention was significantly associated with lower perinatal mortality (OR 0.30, 95% CI 0.14-0.61, p 0.05). CONCLUSIONS: Earlier GA at diagnosis was associated with an increased risk of aneuploidy and worse pregnancy outcomes, including higher risk of perinatal loss. Fetal therapy was significantly associated with lower perinatal mortality. This article is protected by copyright. All rights reserved.