Who is affected by Down syndrome

Down syndrome occurs in all cultures, ethnic groups, socioeconomic levels, and geographic locations.

• About 1,950 babies in the United States were born with Down syndrome in 2004.¹ That's about 1 out of every 600 births.²
• Trisomy 21 is the most common type of Down syndrome, accounting for about 95% of all cases.³
• The risk of a 20-year-old woman having a baby with trisomy 21-type Down syndrome is 1 in about 2,000. By age 45, a woman's risk for having a child with this type of Down syndrome is 1 in 20.⁴

Author:	Debby Golonka, MPH	Last Updated: August 9, 2007
Medical Review:	Adam Husney, MD - Family Medicine Michael J. Sexton, MD - Pediatrics David Smith, MD - Family Medicine
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