What is the prevalence of Down syndrome (Trisomy 21) in New Zealand?

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Last updated: April 25, 2025View editorial policy

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From the Research

Down syndrome occurs in approximately 1 in 1450 live births in New Zealand, according to the most recent and highest quality study available. This prevalence has been influenced by the increased availability of prenatal screening and diagnostic testing, which has enabled expectant couples to make informed decisions about their pregnancies 1. The condition results from the presence of an extra copy of chromosome 21 (trisomy 21), which occurs randomly during cell division in early embryonic development.

Key Points to Consider

  • In New Zealand, prenatal screening for Down syndrome is offered to all pregnant women, typically involving a combination of blood tests and ultrasound scans in the first and second trimesters.
  • The reduction percentage, which is the net result of Down syndrome-related terminations on live birth prevalence, was estimated at 71% for New Zealand, indicating a significant impact of prenatal screening and diagnosis on the prevalence of Down syndrome 2.
  • After birth, early intervention programs are available throughout New Zealand to support development in children with Down syndrome, including physiotherapy, speech therapy, and educational support.
  • These services are coordinated through the New Zealand Down Syndrome Association, which provides resources and advocacy for affected individuals and their families.

Important Considerations

  • Maternal age can influence the risk of having a child with Down syndrome, with women over 35 having a higher chance of having a child with the condition.
  • The total population of people with Down syndrome has been decreasing since 2011 in New Zealand, owing in large part to increased selective terminations 2.
  • Understanding the changing landscape of prenatal services is essential for future investigation into social policies that affect the prevalence of Down syndrome 1.

References

Research

Estimation of the number of people with Down syndrome in Australia and New Zealand.

Genetics in medicine : official journal of the American College of Medical Genetics, 2022

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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