Maternal Age

Risk for Down Syndrome

Risk for any chromosomal abnormality

20

1 in 1667

1 in 526

21

1 in 1667

1 in 526

22

1 in 1429

1 in 500

23

1 in 1429

1 in 500

24

1 in 1250

1 in 476

25

1 in 1250

1 in 476

26

1 in 1176

1 in 476

27

1 in 1111

1 in 455

28

1 in 1053

1 in 435

29

1 in 1000

1 in 417

30

1 in 952

1 in 384

31

1 in 909

1 in 383

32

1 in 769

1 in 322

33

1 in 625

1 in 317

34

1 in 500

1 in 260

35

1 in 385

1 in 204

36

1 in 294

1 in 164

37

1 in 227

1 in 130

38

1 in 175

1 in 103

39

1 in 137

1 in 82

40

1 in 106

1 in 65

41

1 in 82

1 in 51

42

1 in 64

1 in 40

43

1 in 50

1 in 32

44

1 in 38

1 in 25

45

1 in 30

1 in20

46

1 in 23

1 in15

47

1 in 18

1 in12

48

1 in 14

1 in10

49

1 in 11

1 in 7