A 30-year-old G1P0 at 8 weeks’ gestation presents for her first prenatal visit. She has no significant past medical or surgical history. A 29-year-old friend of hers just had a baby with Down syndrome and she is concerned about her risk of having a baby with the same problem. The patient reports no family history of genetic disorders or birth defects.
You should tell her that she has an increased risk of having a baby with Down syndrome in which of the following circumstances?
a. The age of the father of the baby is 40 years or older
The answer is b. The risk of aneuploidy is increased with multiple miscarriages not attributable to other causes such as endocrine abnormalities or cervical incompetence. Paternal age does not contribute significantly to aneuploidy until around age 55, and most risks of paternal age are for point mutations. A 45 X karyotype results from loss of chromosome material and does not involve increased risks for nondisjunctional errors. Similarly, induced ovulation does not result in increased nondisjunction, and hypermodel conceptions (triploidy) do not increase risk for future pregnancies.