Infertility is slightly more common in women. About 40-50% of couples with difficulty conceiving will have some sperm issues, ranging from mild to severe problems. Sometimes this is the only reason for a couple’s infertility, and sometimes male infertility problems and female infertility issues occur together in both partners.
Part of the reason that women have more infertility issues is that getting older often has more effect on female fertility than on male fertility, as a woman makes few, if any, new eggs in her lifetime, with a peak number of eggs at birth. The number and quality of eggs left (ovarian reserve or egg supply) declines in women in their 30’s and 40’s, and rarely in their 20’s. Men have less consistent effects of aging, as they make new sperm all the time, so some men in their 50’s or 60’s may have little or no sperm problems.