AbstractIntroductionAs the prenatal detection rates of congenital heart defects (CHDs) increase, obstetricians are more frequently faced with pregnancies complicated by a fetal CHD. Congenital anomalies in general are associated with preterm birth and fetal demise. The aim of this study was to gain insight into the prevalence of preterm birth and fetal demise in singleton pregnancies with fetuses with isolated CHDs.Material and methodsA geographical cohort study was performed in a large region in the Netherlands. Fetuses and infants from singleton pregnancies diagnosed with severe isolated CHD, born between 1 January 2002 and 1 January 2012, were included. All cases in the CHD cohort were assessed for preterm birth or fetal demise. The proportions of preterm birth and fetal demise were compared with those in a control group and odds ratios were calculated.ResultsThe proportion of preterm births in the CHD cohort (n = 1013) was 9.1% (95% CI 7.3–10.9) compared with 5.6% (95% CI 5.4–5.8) in the control group, with an odds ratio of 1.7 (95% CI 1.4–2.1). The preterm birth started spontaneously in 49.5% and 38.4% were induced. In 15 cases fetal demise occurred (1.5%; 95% CI 0.8–2.2), compared with 0.7% (95% CI 0.6–0.8) in the control group, odds ratio 2.0 (95% CI 1.2–3.4).ConclusionsHigher rates of preterm birth and fetal demise occur in fetuses with isolated CHD compared with the general population. Prenatal specialists should be vigilant for signs of heart failure, premature closure of the foramen ovale or fetal distress in fetuses with isolated CHDs.