PARIS — Agence France-Presse Last updated on Friday, Mar. 13, 2009 10:02AM EDT
Women's pregnancy rates drop and miscarriages increase when the baby's father is older than 40, according to a study to be released today.
It has long been known that a woman's chance of reproducing declines with age once she is in her mid-30s, but the new findings provide the strongest evidence to date that being an older father poses a risk as well.
Researchers in France monitored 21,239 cases of intrauterine insemination (IUI) - a particularly effective type of artificial insemination - in more than 12,000 couples.
As expected, they found that women older than 35 showed significantly decreased pregnancy rates compared with younger women, as well as higher rates of miscarriage.
"But we also demonstrated that the age of the father was important in the rate of pregnancy, with a negative effect for men over 40," said Stéphanie Belloc, a researcher at the Eylau centre for assisted reproduction in Paris and lead author of the study.
"And even more surprising, the proportion of miscarriages went up as well," she added.
Dr. Belloc was to present her research today at the annual meeting of the European Society of Human Reproduction and Embryology in Barcelona.
In IUI treatment, sperm are separated from seminal fluid in a centrifuge. The "washed" sperm are then inserted directly into the uterus in order to enhance the chances of conception.
In most of the cases examined, the couples were being treated because of the husband's infertility, but the findings also apply to other men, the researchers said.
"There is no doubt that we can extrapolate from the study to men in general," co-author Yves Menezo said.
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