Background: Assessment of the effect of fetal diagnosis on the prevalence of congenital heart disease at term requires national ascertainment because referral patterns are not rigorously structured.
Methods: Between 1993 and 1995, all 17 paediatric cardiac centres in the UK submitted to a database lists of all fetuses diagnosed, and all infants needing surgery or interventional catheterisation or dying in the first year of life because of structural heart disease; details included the postal area of residence.
Findings: There were 4799 affected pregnancies, 4165 babies born alive, 1124 fetal diagnoses, and 567 terminations of pregnancy because the fetus had structural heart disease. Thus, a fetal diagnosis was made in 23.4% of affected pregnancies (11.7% of all affected livebirths) with geographical variability in diagnostic rates.
Interpretation: Fetal cardiac screening has an effect on the prevalence and types of congenital heart disease seen at term because many affected pregnancies are terminated. If detection rates of affected fetuses rose nationally to those seen in the 15 postal areas where detection rates were significantly higher than the national average in 1993-95, we would expect about 218 fewer affected individuals to be born annually.