While trying to conceive... the possibility of having a fertility issue can be a sensitive topic.
According to the American Society for Reproductive Medicine ... infertility affects six-point-seven million women in the U-S.
And a new study finds that men are either the sole cause of or contribute to 40-percent of infertile couples.
Now the reason for why this is, is still a question though.
After studying the medical records of nearly 800 men with and without fertility problems, researchers from the State University of New York at Stony Brook reveals infertile men do not have more medical problems than their peers.
They found no relationship between the number of diseases a man had and their ability to conceive a child.
Other studies have found possible answers for the infertility in men.
Scientists at Stanford University think it might be medication interactions.
They compared infertility rates of men both before and after they began taking blood pressure medication... ace inhibitors and beta blockers.... and they found that the risk of fertility problems was about 10-percent higher.
An evaluation of the men showed these drugs affected their sperm concentration and motility.
There was no association between calcium channel blockers and infertility rates though.
Another study out of the University of Utah found that ADHD stimulants can also lower sperm counts and motility.
A Boston University study found another major factor for a man's fertility... how much sleep he gets.
Researchers look at nearly 700 couples found men who slept less than six hours... or more than nine hours a night... were the least likely to conceive a child.
Also, men who said they had trouble sleeping at least half of the time had more infertility problems.
© 2017 NBCNEWS.COM