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By Mayo Clinic staffSome parents have a greater risk of having a baby with Down syndrome. Risk factors include:
- Advancing maternal age. A woman's chances of giving birth to a child with Down syndrome increase with age because older eggs have a greater risk of improper chromosome division. By age 35, a woman's risk of conceiving a child with Down syndrome is 1 in 400. By age 45, the risk is 1 in 35. However, most children with Down syndrome are actually born to women under age 35 because younger women have far more babies.
- Having had one child with Down syndrome. Typically, a woman who has one child with Down syndrome has about a 1 percent chance of having another child with Down syndrome.
- Being carriers of the genetic translocation for Down syndrome. Both men and women can pass the genetic translocation for Down syndrome on to their children.
References
- Down syndrome. National Institute of Child Health and Human Development. http://www.nichd.nih.gov/health/topics/down_syndrome.cfm. Accessed Jan. 9, 2009.
- Barss V, et al. Overview of prenatal screening and diagnosis of Down syndrome. http://www.uptodate.com/home/index.html. Accessed Jan. 9, 2009.
- Down syndrome Q & A. National Down Syndrome Society. http://www.ndss.org/index.php?option=com_content&view=article&id=55:down-syndrome-q-a-a&catid=35:about-down-syndrome&Itemid=75. Accessed Jan. 20, 2009.
- What causes Down syndrome? National Down Syndrome Society. http://www.ndss.org/index.php?option=com_content&task=category§ionid=23&id=60&Itemid=234. Accessed Jan. 20, 2009.
- Genetic conditions: Down syndrome. Genetics Home Reference. http://ghr.nlm.nih.gov/condition=downsyndrome. Accessed Jan. 9, 2009.
- Facts about Down syndrome. National Institute of Child Health and Human Development. http://www.nichd.nih.gov/publications/pubs/downsyndrome.cfm. Accessed Jan. 20, 2009.
- Canick JA, et al. Second trimester maternal serum screening for Down syndrome. http://www.uptodate.com/home/index.html. Accessed Jan. 9, 2009.