Infertility does not have to happen inside the women's body, it can happen in the male reproductive system too. The first step to deciding what the best way to treat the problem is figuring out who has the problem in the first place. Most problems in males have to do with sperm. It could be the amount of sperm being produced, or lack of amount, or it could be the lifespan of the sperm. Other complications and reasons for infertility are problems in the way the sperm is delivered. In some cases the male could have erectile dysfunction, ejaculation issues, or a blockage in the ejaculatory ducts. The male also might not be producing enough sperm, or the sperm he is producing is malformed in some way.
In women the problems are more in numerous, and vary widely. The most common cause would be a problem during ovulation. This could prevent the development of an egg and also could block the fallopian tubes. These problems could be caused by endometriosis, adhesions, or scaring, pelvic inflammatory disease, or poor ovary reserves. Ovarian failure can because of aging, but it can be because of other factors too. Often it is a defect in the anatomy of the female that restricts the egg from being implanted.
Many factors are involved in the reason for infertility, and you need to see a doctor to have those problems diagnosed. The best luck you will have conceiving is if you see a doctor who specializes in infertility problems.