Live birth prevalence of atrioventricular septal defect after the implementation of new prenatal screening guidelines

In 2004, the Danish Health Authority implemented a new guideline on prenatal screening, offering all pregnant women in Denmark a foetal diagnostic ultrasound scan in the first and second trimester of their pregnancy. One of the diagnoses that may be diagnosed prenatally is congenital heart defect including atrioventricular septal defect (AVSD). AVSD is often associated with Down syndrome (DS). After a prenatal diagnosis of AVSD, parents are offered counselling on the impact of the diagnosis on their child's life. The aim of this study was to describe the impact of changes in prenatal screening programmes on the live birth prevalence of AVSD on the island of Funen, Denmark.

This was a registry-based descriptive analysis drawing on data from the EUROCAT Registry of Congenital Malformations for Funen County, Denmark. Cases of AVSD and DS from 1990 to 2018 were included.

Out of 153,757 births, 60 cases of AVSD were registered, with a total prevalence at 3.9 per 10,000 births. Among all cases, 40% had an associated chromosomal diagnosis. The prenatal detection rate increased by 83% after implementation of the new screening programme. This was paralleled by an increase in the number of cases of termination of pregnancy following foetal anomaly (TOPFA) from 3% to 21% (p-value less-than 0.05) and a 21% reduction in live births among infants with AVSD.

A significant increase in the rate of TOPFA was found, with no difference in the distribution of chromosomal or non-chromosomal status, leading to a 21% reduction in liveborn infants with AVSD.

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