Down Syndrome

What increases my risks for having a baby with Down syndrome?

A Answers (4)

  • Any mother, regardless of nationality, race, or behavior, might have a baby with Down syndrome (DS). But, females over 35 have a greater chance than those under 35. This is thought to be the case because the older an egg gets, the greater its risk for abnormal division.
    Also, a mother who has previously had a child with DS has a slight increased risk for a subsequent pregnancy with DS (about a 1 percent chance), and those who are known as balanced carriers (referring to the translocation form of DS) have a greater risk as well.

  • AHealthwise answered

    Certain things increase the chance that you will have a baby with Down syndrome. These are called risk factors. Risk factors may be different based on the type of Down syndrome.

    Trisomy 21

    Trisomy 21 is the most common type of Down syndrome. People with this type have an extra chromosome (47 instead of 46) in every cell. Risk factors for this type include:

    • Being older when you get pregnant. The risk of having a baby with a genetic problem increases as a woman gets older. Many doctors believe that the risk increases for women age 35 and older. This risk keeps rising the older a woman gets.
    • Having a previous pregnancy in which the fetus had Down syndrome. Women who have had a pregnancy with trisomy 21 Down syndrome have a 1-in-100 chance of having another child with the condition.


    This type of Down syndrome is caused by only some cells producing 47 chromosomes. Mosaicism affects up to 3 out of 100 people who have Down syndrome. Risk factors for mosaicism are similar to those for trisomy 21.


    Translocation type is the only type of Down syndrome that may be passed through families, but most of the time it happens randomly. A person with this type has 46 chromosomes, but part of one chromosome breaks and then attaches to a different chromosome. Up to 4 out of 100 people with Down syndrome have the translocation type.

    You may be a carrier of the translocation chromosome if you have:

    • A family history of Down syndrome.
    • Had other children with this type of Down syndrome.

    If you are thinking about becoming pregnant and you're at risk for having a child with Down syndrome, you may want to see a geneticist or genetic counselor. They can help you understand your risk and work with you on genetic testing.

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  • The risk of having a child with Downs Syndrome increases directly with increasing maternal age. For example, it is estimated that a 25 year old mother has a 1/1300 risk of having a Downs child and a 35 year old has a risk of 1/365. Other risk factors include a family history and a previous child with Downs.
  • Maternal age: As women age, there is a greater chance that the cells in her eggs will not divide properly. This increases the risk of having a child with Down syndrome. Women who are 35 years old have a one out of 385 chance that their children will have Down syndrome. Forty-year-old women have a one out of 106 chance of giving birth to children with Down syndrome. By age 45, the risk increases to one out of 30.

    Mothers of Down syndrome children: In general, a woman who has one child with Down syndrome has a one percent chance of having another child with the condition.

    Genetic carriers: Carriers of rearranged chromosome 21 may pass translocation Down syndrome onto their children. The risk of passing the translocation onto a child depends on the parent's gender. Fathers who carry the translocated chromosome have a three percent risk of having children with Down syndrome. Mothers who carry the translocated chromosome have a 12% chance of having children with Down syndrome.

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