An anonymous reader quotes a report from The Guardian: A new study reveals that a couple's chances of having a baby fall with the man's age, to the point that it can have a substantial impact on their ability to start a family. Laura Dodge, who led the research at the Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, said that couples should bear the findings in mind when planning a family. "When making this decision, they should also be considering the man's age," she said. Scientists have long known that a woman's chances of conceiving naturally drop sharply from the age of 35, but fertility research has focused so much on women that male factors are less well understood. To investigate the impact of a man's age on a couple's chances of having a baby, Dodge and her colleagues studied records of nearly 19,000 IVF treatment cycles in the Boston area between 2000 and 2014. The women were divided into four age bands: those under 30, 30-35 year-olds, 35-40 year-olds, and those aged 40-42. The men were divided into the same age brackets with an extra band for the over 42s. Some of the couples had received up to six cycles of IVF. Dodge then looked at how age affected couples' chances of having a live birth. As expected, women in the 40-42 age bracket had the lowest birth rates, and for these women the male partner's age had no impact. But for younger women the man's age mattered. Women aged under 30 with a male partner aged 30 to 35 had a 73% chance of a live birth after IVF. But that impressive success rate fell to 46% when the man was aged 40 to 42. Whether they can hear it or not, the biological clock ticks for men too.