Since pregnant women's average age increased during this time frame, the number of children born with Down Syndrome also increased since occurrence of down syndrome is more likely when the mother is older. However, with such increase in age, more elective pregnancy terminations occurred from 2006 to 2010.

Down Syndrome Trends in Relation to Mother's Age: 1990-2019

Graph - Age of mother and prevalence of down syndrome

The prevalence of giving birth to a baby with Down syndrome is significantly higher in older women (over the age of 35) because as a woman ages, the probability that one of her eggs will contain an excess copy of the 21st chromosome increases greatly. Nearly ½ of babies with Down syndrome are born to women over the age of 35 every year in the United States. 

University of Virginia, Charlottesville

Though the occurrence of Down syndrome is random and not directly correlated with any health, personal or socioeconomic factors, there are two certain characteristics of a parent that increase the likelihood of a child being born with Down syndrome. These two characteristics are: 
- The age of the mother 
- If one or both parents have Down syndrome or a chromosomal abnormality 



Factors that Increase Risk 

CDC. (2017). Data and Statistics on Down Syndrome. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/birthdefects/downsyndrome/data.html

Data and Statistics on Down Syndrome

Who is at risk for Down syndrome? (2022). Https://Www.nichd.nih.gov/. https://www.nichd.nih.gov/health/topics/down/conditioninfo/Risks#

Who is at risk for Down syndrome?

The Age of the Mother

When one or both of the parents has Down syndrome or another variation of chromosomal abnormality, their child is more likely to inherit a chromosomal abnormality, of which Down syndrome is the most common. 

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