There are plenty of rumors and myths surrounding infertility: both for females and males. Male infertility is caused by a number of factors, such as abnormal sperm production, or disruptions in the size and shape of sperm. Low sperm concentration, blocked sperm delivery, and hormonal problems are also often to blame for infertility.

But in addition to genetics and biology, lifestyle and environment play quite a major role too: a man’s age, levels of alcohol and tobacco consumption, possible STD infections, weight, and even exposure to heat can all have an effect on male fertility. “Many men don’t think about their fertility, and avoid learning more due to a fear of the unknown,” Dr. Christopher Sipe of Fertility Centers of Illinois said in a statement. “Learning about basic male infertility helps take the fear and confusion out of conception.” In light of Men’s Health Month, below are several misconceptions about male fertility.

Age

Age is a pretty well-known factor both for men and women when it comes to reproducing and making healthy babies, though there has also been some debate over it. If you’re a 40-year-old man or woman, do you have a lesser chance of reproducing successfully than if you were 25 years old? Some sources claim that a man’s fertility begins to decrease after age 37, but others say that men can safely reproduce up until age 41 or even 45. Either way, it’s widely accepted that the older you get, the less likely you’ll be able to reproduce successfully. Some men have fathered children well into their 60’s or 70’s, though it becomes rarer in those later decades.

“Studies have consistently shown that increasing male age is associated with an increased time to pregnancy and decreased pregnancy rates,” the authors of a 2011 study about age and fertility wrote. “However, only a few studies have examined these outcomes while adjusting for female age… In addition to female age, coital frequency and sexual functioning are variables that affect time to conception and pregnancy rates. Decreased sexual activity can decrease the chances of conception, and erectile dysfunction (ED) increases with age.”

Drugs, Smoking, Alcohol

It’s true that taking part in certain vices will have an impact on male fertility. A recent study published in Human Reproduction was the first and largest study to examine how lifestyle affects sperm morphology, or the size and shape of sperm. Researchers from the Universities of Sheffield and Manchester found that cannabis actually negatively affected sperm, ultimately leading the authors to conclude that marijuana might have adverse effects on fertility. Strangely enough, alcohol and tobacco didn’t show to have any negative effects in that particular study.

But other research has shown the opposite: that tobacco and alcohol does have an impact on male fertility, with some claiming that smoking tobacco might increase chances for infertility in men by 30 percent. The American Society for Reproductive Medicine, meanwhile, estimates that nearly 13 percent of infertility is caused by smoking, due to tobacco’s association with issues like erectile dysfunction or pregnancy complications. Male smokers in particular may suffer decreased quality and motility of sperm as well as lower sperm amounts.

Exposure To Environmental Factors

Though it may sound a little absurd, some studies have also shown that exposure to Radio-frequency electromagnetic radiation (RF-EMR) from cell phones and other small devices could inadvertently damage male fertility. "Given the enormous scale of mobile phone use around the world, the potential role of this environmental exposure needs to be clarified,” one recent study’s author, Dr. Fiona Mathews of the University of Exeter, said in a press release. “This study strongly suggests that being exposed to radio-frequency electromagnetic radiation from carrying mobiles in trouser pockets negatively affects sperm quality. This could be particularly important for men already on the borderline of infertility, and further research is required to determine the full clinical implications for the general population." Another study, released in 2007, showed that an increase of abnormally-sized sperm cells was linked to duration of exposure to GSM phone wave emissions. That same study also found a decrease in motility, or movement, of sperm cells linked to frequency of using cell phones.

Then there's heat exposure, something that has also been proven to negatively impact sperm morphology and male fertility. Exposure to hot baths, tubs, or other high-heat sources has been shown in various studies to impair sperm production. "It has been believed for decades that wet heat exposure is bad for fertility, as an old wives' tale, but this effect has rarely been documented," Dr. Paul Turek, an author of a study and professor at the University of California, San Francisco (UCSF) Department of Urology, said. "We now have actual evidence to show patients that these recreational ativities are a real risk factor for male infertility."

Obesity

Keeping on extra pounds will indeed have an effect on male fertility as well, due to increased levels of estrogen and lower testosterone caused by obesity. “Male obesity in reproductive-age men has nearly tripled in the past 30 years and coincides with an increase in male infertility worldwide,” the authors of a 2012 study on the link between male obesity and infertility wrote in their abstract. “There is now emerging evidence that male obesity impacts negatively on male reproductive potential not only reducing sperm quality, but in particular altering the physical and molecular structure of germ cells in the testes and ultimately mature sperm.”