I believe that higher risk hits even earlier at 35.
HombreSecreto: I believe that higher risk hits even earlier at 35.
The correlation between increasing paternal age and the likelihood of having a child with Down syndrome (trisomy 21) appears to be real - but modest. Maternal age remains the dominant driver of risk. When analyses adjust for maternal age, paternal age generally shows a smaller, independent effect. Some studies even suggest a U‑shaped pattern, with slightly higher risk in very young fathers and in fathers over 40, compared to fathers in their 20s–30s.
Empirical data indicates that around 90–95% of Down syndrome cases originate from maternal nondisjunction, while only 5–10% are paternal in origin. This imbalance suggests that defective sperm rarely succeed in fertilization compared to defective eggs.
In short, the human ovum is a stationary target - if it is defective, it's still a possible target.
The human spermatozoa are the "arrows" flying towards that target - and the MULTIPLE barriers present in the female reproductive tract act as a "Great Barrier" to defective spermatozoa.
Regards,