Immune and non-immune hydrops fetalis in a Saudi tertiary center: etiologies, antenatal predictors, perinatal outcomes, and one-year survival in a seven-year cohort

Background Hydrops fetalis encompasses diverse fetal disorders with high perinatal mortality, and contemporary regional data are limited. Methods We conducted a single-center retrospective cohort study at a Saudi tertiary referral hospital (2016–2022). Pregnancies with antenatal hydrops (≥2 fluid-filled compartments) that were delivered at our center were included and classified as immune or non-immune hydrops fetalis (NIHF). For NIHF, multivariable logistic regression identified predictors of (i) live birth vs. intrauterine fetal death (IUFD)/termination in the antenatal cohort and (ii) one-year survival among live-born infants. Results Of 63,000 deliveries, the hospital-based birth prevalence of antenatally diagnosed NIHF and immune hydrops was 1.84/1,000 and 0.22/1,000, respectively. Among live births, the prevalence was 0.65/1,000 (NIHF) and 0.16/1,000 (immune). In the NIHF antenatal cohort ( n = 116), the outcomes were IUFD 56.9% (66/116), termination 7.8% (9/116), and live birth 35.3% (41/116). Of the 41 live-born infants with NIHF, 43.9% (18/41) survived to one year of age. In the multivariable analysis, the antenatal factors that were independently associated with IUFD/termination were earlier gestational age at diagnosis adjusted odds ratio [aOR 1.20 per week earlier, 95% confidence interval CI 1.09–1.31; p 0.001] and fetal pleural effusion (aOR 6.11, 95% CI 2.07–17.98; p = 0.001). Among live-born infants with NIHF, gestational age at delivery was the sole independent predictor of one-year survival (aOR 1.55 per additional week, 95% CI 1.09–2.22; p = 0.016). In the immune hydrops subgroup ( n = 14), most pregnancies received intrauterine transfusion, and the one-year survival was 71.4% (10/14). Among the ten live-born immune cases, postnatal management was intensive, with intravenous immunoglobulin (IVIG) administration in 100% of cases, double-volume exchange transfusion in 80%, and invasive ventilation in 80%. Forty percent received inhaled nitric oxide, and the median hospital stay was 41 days, reflecting substantial resource use. Conclusions In this seven-year cohort, earlier presentation and pleural effusion identified antenatal NIHF pregnancies at high risk for IUFD/termination, whereas maturity at delivery was the key determinant of one-year survival in live-born NIHF. Immune hydrops showed comparatively favorable survival with fetal therapy. These data provide birth-prevalence benchmarks for a Middle East tertiary center, supporting guideline-based evaluation, timely fetal-therapy referral, and multidisciplinary care focused on targeted diagnosis and intervention, as well as safe prolongation of gestation where feasible.