Genetic risk maternal age

The table below shows the correlation of maternal age (mother's age) and the potential risk of human genetic abnormalities in children.

The first column shows maternal age, the second column shows the most common human chromosomal abnormality, trisomy 21 (Down syndrome), the third column shows all chromosomal abnormalities.

Age of Mother	Risk of Down Syndrome	Risk of 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 384
32	1 in 769	1 in 323
33	1 in 625	1 in 286
34	1 in 500	1 in 238
35	1 in 385	1 in 192
36	1 in 294	1 in 156
37	1 in 227	1 in 127
38	1 in 175	1 in 102
39	1 in 137	1 in 83
40	1 in 106	1 in 66
41	1 in 82	1 in 53
42	1 in 64	1 in 42
43	1 in 50	1 in 33
44	1 in 38	1 in 26
45	1 in 30	1 in 21
46	1 in 23	1 in 16
47	1 in 18	1 in 13
48	1 in 14	1 in 10
49	1 in 11	1 in 8

References

• Hook EB. Rates of chromosome abnormalities at different maternal ages. Obstetrics and Gynecology 58:282-285, 1981 (Data USA sourced)
• Hook EB, Cross PK, Schreinemachers DM. Chromosomal abnormality rates at amniocentesis and in live-born infants. JAMA. 1983 Apr 15;249(15):2034-8. PMID: 6220164
• Schreinemachers DM, Cross PK, Hook EB. Rates of trisomies 21, 18, 13 and other chromosome abnormalities in about 20 000 prenatal studies compared with estimated rates in live births. Hum Genet. 1982;61(4):318-24. PMID: 6891368

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Dr Mark Hill 2009, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G