James' World 2

Obesity is another important risk factor, said Dr. Channa Jayasena, a reproductive endocrinologist at Imperial College London. Fat cells produce an enzyme called aromatase, which converts testosterone to estrogen. Lower testosterone makes it harder to maintain an erection and slows sperm production. Every inch increase in a man’s waistline has been associated with an approximately 3 percent drop in sperm concentration, according to a study from the Harvard T.H. Chan School of Public Health. Numerous studies have shown that weight loss programs can raise sperm count in obese people.

Experts also said to avoid testosterone therapy unless you have a medical test confirming that you have a deficiency.

Gently stretching your hips, glutes, and hamstrings can help relax those muscles — as can diaphragmatic breathing. If you are experiencing serious long-term symptoms, however, Dr. Ziegelmann suggests seeking a pelvic floor physical therapist who can advise the best ways to loosen up.

Your age can influence sperm quality …

Multiple experts said they wished more men knew how age could affect sperm quality.

“There’s a misconception that if you can get an erection and ejaculate, you’re fertile,” said Dr. Michael Carroll, a reproductive scientist at Manchester Metropolitan University in England.

Sperm quality tends to deteriorate with age, affecting how well they swim, damaging the DNA they carry and even increasing the chances of complications during pregnancy, Dr. Chen said. There’s no clear cutoff age, since DNA damage accumulates throughout a man’s life. One study found that the risk of miscarriage was 43 percent higher when the father was older than 45, compared to someone in their late 20s. Urologists urged men to consider their age when planning a family, much as many women already do.

“Fertility is a team sport,” Dr. Chen said. “And men have increasingly more to do with outcomes than what we previously thought.”

… and so can other lifestyle factors.

Smoking, alcohol consumption and nutrition also play a large role in sexual function. A high-fat, high-sugar diet results in an increase in certain chemicals — known as reactive oxygen species — that cause wear and tear on cells, including those within the testes. Dr. Carroll pointed out that the Mediterranean diet, which includes foods with higher levels of antioxidants, was associated with healthier sperm.

Obesity is another important risk factor, said Dr. Channa Jayasena, a reproductive endocrinologist at Imperial College London. Fat cells produce an enzyme called aromatase, which converts testosterone to estrogen. Lower testosterone makes it harder to maintain an erection and slows sperm production. Every inch increase in a man’s waistline has been associated with an approximately 3 percent drop in sperm concentration, according to a study from the Harvard T.H. Chan School of Public Health. Numerous studies have shown that weight loss programs can raise sperm count in obese people.

Experts also said to avoid testosterone therapy unless you have a medical test confirming that you have a deficiency.

“It’s marketed to younger men as, ‘If you want big muscles, if you want erections that will last forever, if you want to look like a real man, then take testosterone,’” Dr. Modgil said. Yet few are aware that it can also interrupt sperm production and potentially reduce fertility.

Exercise in moderation while trying to start a family.

Regular physical activity can enhance your fertility, but avoid extreme training regimens if you are trying to conceive.

Some evidence suggests that high-intensity exercise can cause a stress response that interrupts testosterone production, reducing sperm production, Dr. Carroll said. Pushing the body to its limits may also increase the production of the chemicals that damage DNA, he said.

Cycling may come with additional risks, Dr. Bole said. “You get scrotal compression for a long period of time, and you have tight clothing, which has the potential to elevate the temperature of the testes.” Short recreational rides aren’t likely to do much harm, she added, but longer training might cause problems.

That doesn’t mean you have to give up your bike touring. But if you are concerned about your fertility, practice more moderate exercise, Dr. Carroll said. Keep in mind it takes about two months for newly produced sperm to fully mature, so don’t expect lifestyle changes to have an immediate effect.

Squeamishness is the enemy of health.

Experts said that a reluctance to discuss their private parts can prevent men from visiting a urologist and being screened for things like testicular cancer.

“When caught early, it has nearly a 98 percent cure rate,” said Dr. Juan Andino, a urologist at UCLA Health who urges men to make a habit of checking their anatomy regularly.

One common reason some men avoid screening is the size or shape of their penis, experts said. These worries can contribute to anxiety, depression, and sexual dysfunction. In extreme cases, they can become a form of body dysmorphia that significantly impairs daily life, Dr. Carroll said.

He noted that pornography can set unrealistic standards that leave many people feeling inadequate. It often reassures men, Dr. Carroll said, to know the average erect length is smaller than many assume: around 5.2 inches.

He also warned against treatments claiming to enhance penis size and said simply trimming pubic hair could leave some men feeling more confident.

Remember that your urologist has seen it all before, Dr. Ziegelmann said. And a frank conversation can go a long way to assuaging fears.