A new study shows that as men age they have a harder time helping their partners to conceive. The study also found women whose partners are five or more years older than themselves have less chance of conceiving in under a year compared to women whose partners are the same age or younger. The study examined nearly 15,000 planned pregnancies from the Bristol area of England from 1991-92. Researchers say it is the first clear evidence that the age of the man, as well as the woman, is an important factor in conception. Experts say the findings show a more dramatic decline in male fertility than they had expected.
Researchers say a number of factors seem to affect male fertility as they grow older.
One of the biggest factors is that older men tend to have sex less often, which means they're less likely to have sex during a woman's fertile period, says Ford. Genetic and environmental factors may also affect sperm production and decrease male fertility. Ford's study is published in the current issue of the journal, Human Reproduction.