However, there are incidences of couples not conceiving children, no matter how much sex they have. The main reason for this would be that either one, or both of them, is not fertile. In other words, they do not have the capacity of conceiving because of low fertility in them. Usually, when the couple does not conceive a baby, it is thought that it is because of low fertility on the woman's part that they cannot conceive. However, this is not true. Statistics have shown that the problem is usually slightly higher on the woman's side, than the man. This means that not only women, but men too may be the cause for not being able to conceive. This is because they will be low on their fertility.

There are basically different factors that contribute to a male's fertility; however, the most common one is the blockage of the tube that carries their sperms. Like in the case of women, this blockage can be a scar tissue that is caused by Chlamydia, which is a sexually transmitted disease. This disease does not actually have any symptoms and will be found out only when the damage to the male's fertility is done.

Then there is another common problem amongst men that leads to infertility, and that is variocele. According to research, about 14% of the men seeking help for infertility suffer from variocele. The meaning of variocele is the twisted and enlarged varicose vein that is found in the connective cord of the testicles of the man. This condition is actually found in about one-fifth of all men; however, it does not always impair the fertility of all the males. Its actual function is not known; but it is has been found to be more common in men who seek help for their fertility than in the general male population. Variocele is a condition that can be treated, via surgery. With this surgery, about a third of the couples who complained of not being able to conceive usually conceive within the first year of this surgery.

Mumps is a childhood disease that does not seem to have any consequences to it like scars. However it is known that it can cause a lowered fertility in a man, if mumps is contracted after puberty of the man. Even all other infections like glandular infections can damage sperm production in a man, and impair its normal fertility. Obesity is another factor that is though to cause a man to experience infertility. Along with all these causes, the side effects of drugs and other chronic medical conditions also tend to lead to male infertility.