There are a few different factors that increase the risk of Down syndrome, which is a lifelong genetic condition that are caused by chromosomal abnormalities that appear while the fetus is still developing. In general, the two most significant factors that increase the risk of Down syndrome include the age of the mother, and a family history of the condition. This may mean that a parent or family member is simply a carrier of Down syndrome, but does not actually have the condition, or that a family member or sibling was born with it. The presence of Down syndrome genes in a family is one of the most significant factors that increases the risk that another baby will have the condition.
Doctors have determined that women who get pregnant later in life present more of a risk of having a baby with Down syndrome. In general, the risk of Down syndrome begins to increase at age 35, and then continues to increase each year that a woman remains of childbearing age. There are tests that can be performed while a woman is pregnant that can assess the risk that the baby will be born with Down syndrome, in order for women to have as much information as possible. Some of these tests can return false information, and a doctor might order additional, slightly riskier tests to determine for sure if the fetus has Down syndrome if another risk factor is present.
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The second factor that increases the risk of Down syndrome is family history of the condition. If a family member has Down syndrome, it is possible that a parent is a carrier of the gene, and could potentially pass it on to the baby. If a brother or sister in the family has Down syndrome, or if a fetus was determined to have the condition in the past, this also makes it much more likely that the condition will appear again.
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Aside from these factors that increase the risk of Down syndrome, medical research has not identified any other behavioral or environmental factors. It is possible for the condition to occur randomly, without a medical explanation that can be identified. Specific questions about risk factors or genetic predisposition should be directed to a doctor. He or she can provide specific advice and information about what should be expected through parenting a child with Down syndrome, and specific health concerns that can be associated with the condition, in addition to expected changes in physical appearance and other intellectual characteristics.