Determinants of fetal echogenic intracardiac focus and its association with pregnancy outcomes: links to congenital heart disease and chromosomal abnormalities

Objective To characterise the population distribution of fetal echogenic intracardiac focus (EIF), identify associated maternal factors, and evaluate its associations with congenital heart disease (CHD), chromosomal abnormalities, and perinatal outcomes, providing evidence for risk-stratified clinical management. Methods Pregnant women who underwent routine prenatal anatomic ultrasound at our medical university between January 2024 and December 2025 were included in a case–control study. In Part 1, 846 fetuses with EIF and 850 controls were analysed to describe EIF distribution patterns and associated factors. In Part 2, 721 EIF fetuses were followed up; CHD and chromosomal abnormality rates were compared between isolated single left-ventricular EIF and right-sided and/or multiple EIF, and perinatal outcomes were assessed. Results The overall detection rate of EIF was 13.74%, with isolated single left-ventricular EIF being the most common pattern (69.62%). In multivariable logistic regression, maternal age (OR 1.093, 95% CI 1.060–1.127) and maternal autoimmune disease (OR 1.915, 95% CI 1.315–2.787) were independent risk factors for EIF, whereas maternal obesity was inversely associated with EIF (OR 0.666, 95% CI 0.481–0.923). On follow-up, the right-sided and/or multiple EIF group had higher rates of CHD (13.36%) and chromosomal abnormalities (4.15%) than the isolated single left-ventricular EIF group (9.13% and 1.19%, respectively; both P<0.05). Multivariable analyses confirmed independent associations of right-sided and/or multiple EIF with CHD (OR 1.785, 95% CI 1.077–2.957) and chromosomal abnormalities (OR 7.050, 95% CI 1.693–29.357). Increased nuchal translucency (NT) thickness was a strong predictor of chromosomal abnormalities (OR 18.42, 95% CI 6.316–53.723). Gestational age at delivery and Apgar scores did not differ between groups, although birth weight was slightly lower in the right-sided and/or multiple EIF group. Conclusions EIF is common at mid-trimester screening. Isolated single left-ventricular EIF is usually a benign variant and does not warrant routine intervention. In contrast, right-sided and/or multiple EIF is significantly associated with CHD and chromosomal abnormalities and should prompt comprehensive assessment incorporating maternal age, NT, and other ultrasound soft markers to guide risk-stratified management. Maternal age and autoimmune disease are independent determinants of EIF, while the inverse association with obesity may reflect detection bias.