A factor that increases the probability of having a baby with Down syndrome is
A) increased age of mother or father.
B) parents' use of tobacco.
C) parents' use of alcohol.
D) a defective XY chromosome pattern.

Question

Quizplus · Accepted Answer

Increased age of the mother or father is a well-known risk factor for having a baby with Down syndrome. The risk increases significantly for women over 35 years and men over 40 years of age. Tobacco and alcohol use or a defective XY chromosome pattern are not known to increase the likelihood of having a baby with Down syndrome.

A Factor That Increases the Probability of Having a Baby