Research from France, which looked at more than 12 000 couples, found that once a man is over 35, it is more difficult for the woman to fall pregnant, and, once she does, she is more likely to suffer a miscarriage. This suggests that the age of the father is just as important as the age of the mother for couples wanting to fall pregnant.
The research was led by Stephanie Belloc, of the Eylau Centre for Assisted Reproduction in Paris, France. Her team studied more than 12 000 couples who underwent more than 21 000 intrauterine inseminations, using the male partner's sperm rather than donated sperm. For each insemination the sperm were examined for sperm count, motility and morphology and the rate of pregnancy and the success of any resulting pregnancy was monitored. The researchers then analyzed the results, distinguishing between male and female factors in influencing outcomes for each IUI case.
The results showed that maternal age was closely linked to decreased pregnancy rate, which was 8.9% in women over 35 compared to 14.5% in younger women. However, the researchers found that the father's age was also important, not only on pregnancy rates, but perhaps more surprisingly, on the rate of miscarriage, with a pronounced negative effect once the father was over 35 years of age.
Experts think that the decrease in male fertility after the age of 35 is as a result of DNA fragmentation.
