Trisomy 21 is most common in mothers of the ________ age group.

Correct answer: D. 40 to 45

A. 15 to 19
B. 20 to 34
C. 35 to 39
D. 40 to 45

Explanation

The risk of nondisjunction and therefore trisomy 21 rises markedly with maternal age, with the highest risk among the listed groups at 40 to 45 years. Students may choose 35 to 39 because risk begins increasing substantially after 35, but the older group has the greater incidence.

Last updated 31 August 2026

Trisomy 21 is most common in mothers of the ________ age group.

Related questions