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It takes two to make a baby. Although a woman will carry and deliver the child, a man also has a leading role in pregnancy. For fertilization to occur, his sperm must be healthy and strong enough to reach and penetrate the woman's egg.
To make this process happen, a man must be able to have and keep an erection, possess enough sperm that are the right shape and move in the right way, and have enough semen to carry the sperm to the egg, suggests the U.S. Office on Women's Health. A problem in any step in this process can cause trouble conceiving.
A variety of factors, from genetics and lifestyle to environmental exposures and hormones, can affect a man's fertility, so it's difficult to isolate the exact cause for infertility, said Dr. Jared Robins, chief of reproductive endocrinology and infertility at Northwestern Medicine's Fertility and Reproductive Medicine in Chicago.
When asked for his most important recommendation for men who want to start a family, Robins said, "A man should make sure he has a happy, healthy lifestyle — and a good relationship."
Robins said one of the problems he sees is that when couples become so focused on fertility, they essentially stop having sex until they think it's the best times to conceive. "Their sex lives become focused on pregnancy, so infrequent sex can be a problem in these couples."
Male reproductive system
Before understanding the best practices for getting pregnant, it's important to first understand the male's role in the creation of sperm and the fertilizing of the egg. The male reproductive system includes the testicles, which produce testosterone and sperm. It takes roughly 72 days for sperm to be created, and sperm are stored in the epididymis (the outer structure of the testicles) for anywhere from 15 to 25 days. Here, the sperm mature and develop the ability to swim.
When a male ejaculates, the sperm move through the vas deferens tubes of the penis. The liquid for "swimming" is provided by the seminal vesicles and prostate gland. The sperm then move through the woman's cervix, into the uterus and up into the fallopian tubes. If an egg is present, it is fertilized there, before moving down the tubes to the uterus and continuing to grow. [Related: Trying to Conceive: 12 Tips for Women]
Here are 12 tips for men who want to improve their fertility.
Lose extra pounds
Studies have suggested that couples in which the man is overweight or obese and the woman is of normal weight take longer to conceive than couples with no weight problems.
Some research has also shown that being overweight or obese affects a man's sperm quality, reducing sperm counts and decreasing their ability to swim, as well as increasing damage to genetic material (DNA) in sperm, according to The American Society for Reproductive Medicine.
A recent study found that overweight and obese men were more likely to have low sperm counts or a lack of viable sperm compared with normal-weight men, possibly making it harder for these men to father a child. The researchers suspect that too much body fat may be linked with changes in testosterone and other reproductive hormone levels in men.
Get health conditions under control
Effectively managing chronic medical conditions, such as high blood pressure and diabetes, may improve a man's chances of getting his partner pregnant, suggests the American Society for Reproductive Medicine. Other medical conditions, such as cystic fibrosis or varicoceles (enlarged veins in the scrotum that cause overheating), may also affect male fertility, according to the Centers for Disease Control and Prevention.
In addition, some medications used to treat high blood pressure (beta blockers), depression and anxiety (SSRIs), pain (long-term opiates), and an enlarged prostate (finasteride) could have a negative influence on fertility. Supplemental testosterone can also decrease sperm production.
Some chemotherapy drugs and radiation treatments for cancer can cause permanent infertility, according to the Mayo Clinic.
A man should speak to his doctor if the medication he is taking might interfere with his ability to father a child.
Eat healthy foods
"The role of diet in male fertility is unclear," Robins told Live Science.
Even though the science may be inconclusive, it still makes sense for men to eat a variety of healthy foods, including plenty of fruits and vegetables, which are rich sources of antioxidants that may help to produce healthy sperm. Men should also consume fiber-rich foods, healthy monounsaturated fats and moderate amounts of lean protein.
Robins said men frequently ask him whether drinking soda can decrease their sperm counts. He said he tells them there's no good evidence to support that caffeine has any effect on men's fertility.
Get regular physical activity
Robins said he encourages men to get regular exercise because it helps reduce stress, makes men feel better about themselves and benefits their long-term health.
While being physically active is beneficial, some studies have suggested that overly intense exercising and strenuous training schedules in men, such as triathletes and marathon runners, may be detrimental to their fertility.
Researchers have also looked at whether bike riding can affect sperm, because the sport involves long periods of sitting in a position that increases scrotal temperatures as well as bouncing and vibrations that could cause trauma to the testicles. (A few studies have suggested that long-distance truck drivers may also have more fertility problems for similar reasons as avid male cyclists.)
One study found that men who attended fertility clinics and reported they rode bicycles for at least five hours a week were more likely to have low sperm counts and poor sperm motility compared to men who did other forms of exercise and those who did not exercise.
Other research has suggested that bike riding in men is linked with a higher risk for erectile dysfunction. But there's little data on whether or not cycling actually impacts sperm function, Robins said.
Take a daily multivitamin
Robins tends to recommend that men take a daily multivitamin. "There is little likelihood of harm, and some potential benefits," he said.
Many multivitamin formulations for men might include antioxidants, such as vitamins C and E, and the minerals selenium and zinc. Some research has found that antioxidants may cause a slight increase in sperm count and movement, according to the American Society for Reproductive Medicine.
It makes sense that antioxidants may improve sperm quality because they can protect against free radicals, which can cause damage to DNA within sperm cells, Robins said.
Be conscious of age-related fertility changes
Men also have a ticking biological clock, but they experience fertility declines later in life than women do.
In men over 50, there is a decline in testosterone levels, which can impact sperm function, Robins said. As men get older, there is also a fall off in the number of healthy sperm and the movement of sperm. Older men can also have more DNA damage in their sperm. These changes could mean it takes longer for a couple to have a baby.
As men get older, there is also a greater risk for genetic abnormalities in their sperm. Research has found that older men are more likely than younger men to father a child born with autism, schizophrenia or Down syndrome.
Ditch the butts
Smoking is linked with reduced sperm quality: Research has shown that male smokers are more likely to have low sperm counts and decreased sperm movement, and they have higher numbers of abnormally shaped sperm, according to the American Society for Reproductive Medicine.
Smoking might also decrease sperm's ability to fertilize a woman's egg. These are all good reasons why aspiring dads should take steps to quit smoking.
Prospective fathers should also avoid marijuana and other recreational drug use, including anabolic steroids for bodybuilding, because some studies suggest these substances may also negatively affect sperm production, Robins said.
Ease up on heavy drinking
Many women will steer clear of alcohol when they want to become pregnant, and their partners could also use this as an opportunity to cut back on beer, booze and binge drinking. Research has found that heavy drinking in men can reduce sperm quantity and quality.
When a couple is trying to conceive, men should limit alcohol to low or moderate amounts.
Make healthy lifestyle choices
Environmental exposures may have negative reproductive consequences for men. Exposure at work to certain toxic chemicals, such as those used in dry cleaning and printing, pesticides used in agriculture, and heavy metals in industrial jobs, might reduce fertility in men, said the American Society for Reproductive Medicine.
Men who are concerned about chemicals in the workplace should ask their employers for a copy of the business's Material Safety Data Sheet (MSDS), which should detail any and all chemical exposure at that place of employment. The CDC also offers information on avoiding workplace hazards like chemicals or radiation, which may affect reproductive health.
One small study about men using laptops received plenty of media coverage when it reported that men who placed the computers on their laps may be more likely to have damaged sperm and decreased sperm motility. But these conclusions were "jumping the gun," Robins said. It's unclear how much time the men spent with the laptop in close proximity to their testicles, he explained, and it's also unclear whether the effects may have been caused by heat or if they resulted from radiation due to the use of a wireless connection.
A few studies have also suggested that regularly keeping a cellphone in the front pant's pocket can affect sperm count. But Robins said there has been no research linking this finding to a man's inability to father a child.
Boxers or briefs?
"This is everyone's favorite question," Robins said, chuckling.
But there's not a lot of science to suggest that switching from briefs to boxers improves a couple's odds of getting pregnant.
Although a man's underwear choice may affect his scrotal temperature and reduce sperm quality, most studies have demonstrated no real difference between boxers and briefs in terms of their impact on male fertility, Robins said.
Beware of the heat
Frequent visits to and long stays in hot tubs, saunas and steam rooms could increase scrotal temperatures, which may decrease sperm counts and sperm quality.
But this heat exposure does not have a permanent impact on sperm, Robins said.
Reduced sperm counts may be only temporary and could return to normal in a few months once a man stops going into a hot tub or sauna.
Know when to get help
Robins said he tells couples that a woman who is under the age of 35 and her partner should try to become pregnant for one year. If they don't achieve success in that time, that's when they should seek an infertility evaluation.
For women who are 35 or older, the time before seeing an infertility specialist shortens to six months in couples who are having sex regularly without using birth control, he noted.
Elaine J. Hom contributed to this article.