Do your sperm pass muster? Despite several months of effort, you and your partner haven't yet conceived. You're not ready to seek a fertility evaluation, but you might be wondering whether you're doing all you can to make sure you have healthy sperm. Male fertility depends on sperm quality and quantity, which can be affected by a variety of things. While you may not be able to control all the factors that could improve your fertility, there are steps you can take to maximize your fertility and make sure your sperm are top performers. To achieve its goal, sperm must have three things going for it:

  • Quantity. You're most likely to be fertile if you have more than 20 million sperm per milliliter of semen. However, researchers are finding that having healthy sperm (the quality) may be just as important as the total amount of sperm you produce. Of the millions of sperm in the ejaculated semen, only about 200 actually reach the egg in a woman's fallopian tube.

  • Quality. It's not enough just to have enough. Sperm shape and structure (morphology) are equally important. You are most likely to be fertile if more than one-third of your sperm are of normal shape and structure. A normal sperm has an oval head and a long tail that propel it forward. Sperm with large, small, tapered or crooked heads or kinky, curled or double tails are less likely to fertilize an egg.

  • Motility. To reach the target, your sperm have to move. Riding the semen wave will only take the sperm so far. To reach the egg, sperm have to move on their own—wriggling and swimming the last few inches to reach and penetrate the egg. Sperm movement is an important characteristic of healthy sperm. You're most likely to be fertile if at least half of your sperm are moving.

What can you do to produce high-quality sperm? It takes only one sperm cell to fertilize an egg. With millions of sperm vying for the chance, you'd think each act of intercourse between you and your partner would have excellent odds of resulting in pregnancy. In fact, it may take many attempts before you succeed, even if you're both healthy and your timing is right—that is, you have sex in the days leading up to ovulation when the egg is released from the ovary. Here's what you can do to increase your chance of contributing enough hardy, energetic sperm to get the job done:

  • Take a multivitamin. A daily multivitamin can help provide selenium, zinc and folic acid—trace nutrients that are important for optimal sperm production and function.

  • Eat plenty of fruits and vegetables. These foods are rich in antioxidants, which may help improve sperm health.

  • Reduce stress. Stress might interfere with certain hormones needed to produce sperm. Stress can also decrease sexual function.

  • Get regular exercise. Physical activity is good for reproductive health as well as your overall health.

  • Watch your weight. Too much or too little body fat may disrupt production of reproductive hormones, which can reduce your sperm count and increase your percentage of abnormal sperm.

Caution: Hazardous to sperm Even under the best circumstances, only 50 to 70 percent of a man's sperm are healthy enough to fertilize an egg. Sperm can be especially vulnerable to environmental factors, such as exposure to excessive heat or toxic chemicals. To protect your fertility:

  • Watch out for toxins. Experts think heavy metals used in industrial workplaces, pesticides and chemicals in solvents might have an effect on sperm quantity and quality.

  • Quit using tobacco. The sperm of men who smoke may be misshapen and may move more slowly than those of nonsmokers. Smoking can also damage your sperm's DNA.

  • Limit alcohol. Heavy drinking may reduce the quality and quantity of sperm. Limit alcohol to no more than one or two drinks a day.

  • Steer clear of illicit drugs. Marijuana can decrease sperm density and motility and increase the number of abnormal sperm. Cocaine and opiates can contribute to erectile dysfunction, and amphetamines can decrease sex drive.

  • Avoid hormone havoc. Anabolic steroids, usually taken illegally, can shrink the testicles and drastically reduce fertility. Anti-androgens and testosterone supplements also decrease fertility.

  • Avoid lubricants during sex. Personal lubricants, lotions and even saliva can interfere with sperm motility. However, vegetable-oil-based lubricants are okay.

Adopting healthy lifestyle practices to preserve your fertility—and avoiding things that can damage it—may improve your and your partner's chances of conceiving a child. But you still may not become a father on your first—or even 51st—try. If you and your partner haven't achieved a pregnancy after a year of unprotected intercourse, see your doctor and get a semen analysis. About 25 percent of couples have trouble conceiving at some point, and this number increases with age. Forty percent of infertility can be traced to the man alone, but often it's a combination of both the man and woman. A fertility specialist can identify the cause of the problem and provide treatments that may help place you and your partner on the road to parenthood.