Recent trends in the birth prevalence of Down syndrome in China: impact of prenatal diagnosis and subsequent terminations.

OBJECTIVE

This study aims to analyze recent trends in Down syndrome (DS) prevalence in China and evaluate the impact of prenatal diagnosis and subsequent terminations.

DESIGN

A birth defects surveillance-based retrospective study was adopted.

METHODS

On the basis of the 1996 to 2011 surveillance data for DS from Chinese Birth Defects Monitoring Network, we examined the total prevalence ratio (TPR), perinatal prevalence ratio (PPR) and percentages of prenatally identified cases and of terminations by periods (before and after 2003), birth area, gender and maternal-age classifications.

RESULTS

Down syndrome TPR was 3.05 per 10 000 births during 2003 to 2011, with significant differences between urban-rural, gender and maternal-age groups. DS PPR during 1996 to 2011 was 1.99 per 10 000, presenting an increasing trend till 2003 but a decreasing tendency since then. The proportion of DS diagnosed prenatally increased from 7.55% during 1996 to 2002 to 47.70% during 2003 to 2011, varying by birth area and maternal age. During 2003 to 2011, the high termination rate led to 55% reduction in the overall DS PPR and 62% and 36% decreases in urban and rural PPRs.

CONCLUSION

The important reduction in the PPR suggests that current strategies in China for the prenatal screening and diagnosis of DS are effective. However, significant urban-rural variations in TPR and PPR indicate an urgent need to strengthen prenatal care for DS in rural regions.