French researchers have found out that while mother age is an important factor for people who want to have children, fertility is also affected by the age of the father. The study was made public on Monday, at the European Society of Human Reproduction and Embryology conference that took place in Barcelona, Spain.

The team of French researchers looked at about 12,000 couples who came to fertility clinics in France. For these couples, 21,239 artificial intrauterine inseminations have been made. Most of the couples came to the clinics because the husband had fertility problems.

Researchers took into consideration three factors regarding the sperm samples that were used for the inseminations: sperm count, morphology and motility. Once these analyses were made, the team observed the pregnancy, delivery and miscarriage rates. After looking at all of these factors, the team of scientists reached the conclusion that the risk of miscarriage was 35 percent for couples in which the man was over 40 years of age. The percentage dropped dramatically to 10 to 15 percent for men that were below the age of 30.

According to the Washington Post, Dr. Stephanie Belloc, of the Eylau Center for Assisted Reproduction, said that “how DNA damage in older men translates into clinical practice has not been shown up to now. Our research proves for the first time that there is a strong paternal age-related effect on IUI outcomes, and this information should be considered by both doctors and patients in assisted reproduction outcomes.”

The study is of great importance for couples that plan to have children. Until now, experts considered only mother age to be a factor of influence, but couples should pay attention to the father as well, if they are to take into account the results of the French study.