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Down Syndrome Risk
The older a woman is when she becomes pregnant, the greater the risk her child has of being born with Down syndrome. Parents who already have a child with the condition have about a 1 percent chance of having another child with the disorder, regardless of maternal age. If one of the parents is a balanced translocation carrier, that may also increase the risk.
There are several established risk factors for Down syndrome, including:
- A previous Down syndrome baby
- Increasing maternal age
- Being a carrier of a balanced translocation.
For parents of children with Down syndrome, there is about a 1 percent chance that another Down syndrome child will be born in a subsequent pregnancy, regardless of maternal age.
The likelihood that a woman under 30 who becomes pregnant will have a baby with Down syndrome is less than 1 in 1,000, but the chance of having a baby with Down syndrome increases to 1 in 400 for women who become pregnant at age 35. The likelihood of Down syndrome continues to increase as a woman ages, so that by age 42, the chance is 1 in 60 that a pregnant woman will have a baby with Down syndrome, and by age 49, the chance is 1 in 12.
The Down syndrome risk by age is broken out in the following table.
|
Mother's Age
|
Incidence of Down Syndrome
|
|
Under 30
|
Less than 1 in 1,000
|
|
30
|
1 in 900
|
|
35
|
1 in 400
|
|
36
|
1 in 300
|
|
37
|
1 in 230
|
|
38
|
1 in 180
|
|
39
|
1 in 135
|
|
40
|
1 in 105
|
|
42
|
1 in 60
|
|
44
|
1 in 35
|
|
46
|
1 in 20
|
|
48
|
1 in 16
|
|
49
|
1 in 12
|
Many specialists recommend that women who become pregnant at age 35 or older undergo prenatal screening and/or testing for Down syndrome.
(Click Prenatal Screening for Down Syndrome for more information.)
Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD