Increasing Overall Rates of Prenatal Diagnosis Benefit Previously Disadvantaged Anatomic and Sociodemographic Subgroups

BACKGROUND: To understand which sociodemographic and anatomic groups have benefited from increases in prenatal diagnosis (PND) of congenital heart disease (CHD), we compared factors associated with overall and earlier (≤22 weeks) PND from 2006 to 2019. METHODS: A New Zealand population-based cohort study of all major CHD (death or intervention by 1 year) from 20 weeks' gestation. National cardiac, mortality and governmental data sets were linked for case ascertainment and to obtain the type and timing of diagnosis, maternal age, ethnicity, New Zealand Index of Socioeconomic Deprivation quintile, and domicile. RESULTS: The relative increase in PND between the first and last 5 years was greatest in critical CHD subtypes (death or intervention <1 month), particularly coarctation (124%), d-transposition (78%) and conotruncal anomalies (71%), and in previously disadvantaged groups including indigenous Māori (104%), Pacific (53%), New Zealand Index of Socioeconomic Deprivation quintile 5 (most deprived) (79%) and remote domicile (73%). When adjusted for anatomic factors, PND in the first 5 years was associated with ethnicity (Asian, risk ratio [RR] 1.35, 1.05-2.1.73; European, RR 1.33, 1.11-1.61 versus Māori), New Zealand Index of Socioeconomic Deprivation quintile 1-4 versus 5 (RR 1.27, 1.07-1.50) and domicile in major metropolitan areas (RR 1.18, 1.01-1.37). These factors were not associated with PND in later years. Earlier PND was associated with ethnicity, New Zealand Index of Socioeconomic Deprivation and domicile in the first 5 years and with ethnicity and time of obstetric booking in the last 5 years. CONCLUSIONS: An increase in PND has benefited previously disadvantaged sociodemographic groups and cardiac conditions where a delayed diagnosis is most threatening to life. Persistent associations between earlier PND and sociodemographic factors require further investigation.