Although the woman is the one who carries and delivers the baby, the male partner also plays a leading role in the process. After all, it takes two to make a baby! Women can do their part after the sperm reaches her egg, but if the sperm isn't healthy and strong, then fertilization may not occur.
The U.S. Office on Women's Health (OWH) suggests that men need to have enough sperm of the right shape and that move in the right way to make its way to the egg. There are a variety of factors that affect a man's fertility so it may be difficult to isolate the exact cause if a man is experiencing this.
Life Science outlines 12 tips for men trying to conceive.