Male Biological Clock Miscarriage

Tick Tock

A new study suggests that the rate of pregnancy decreases and the rate of miscarriage

increases when the father is older than 35 years of age. So told Dr. Stéphanie Belloc, of the Eylau Centre for Assisted Reproduction, Paris, France, at the 24th annual conference of the European Society of Human Reproduction and Embryology held on July 7, 2008. This is the first time that a strong paternal influence on conception and miscarriage has been demonstrated.

Dr. Belloc and her research team studied results from 21239 intrauterine insemination procedures (IUIs) in which the husband's semen was used. Most of these cases involved treatment due to the husband's infertility. The sperm of each partner was examined for sperm count, motility, and structure prior to IUI. Miscarriage and delivery rates were recorded with scientists attempting to weed out factors related to other pregnancy-related issues.

It has long been known that maternal age correlated to a decreased rate of pregnancy and the study bore this out with women over the age of 35 showing an 8.9% decreased rate of pregnancy compared to 14.5% in younger women. Miscarriage rates bore a similar association. However, paternal age as an important factor in pregnancy rates was the surprise in this study, with men over 35 causing their partners to have a decrease in pregnancy rates and an increase in the rate of miscarriage.

While many previous reports had shown that sperm declines with a man's age in both count and quality, there had been no proof that paternal aging had a specific effect on a couple's fertility.

Dr. Belloc commented that it was known that couples where the male partner was older took longer to conceive, but there had never been any definitive clinical proof that miscarriage rates increased with paternal age. Recent studies had shown a relationship between DNA damage and paternal age, and this had suggested that further studies, such as this one, be carried out.

The study, though quite large in scale, will be expanded during the next several years with the inclusion of more couples. Scientists hope that further study will bear out the results obtained thus far, since the research has important implications for couples who are trying to conceive.


According to Dr. Belloc, IVF or ICSI should be suggested to infertile couples who are over the age of 35 years. "In IVF, the zona pellucida (the outer membrane of the egg) seems to be an efficient barrier in preventing the penetration of sperm with DNA damage, and in ICSI, the best sperm can be selected out for use. These methods, although not in themselves a guarantee of success, may help couples where the man is older to achieve a pregnancy more quickly, and also reduce the risk of miscarriage," she says.

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