Uterine & Tubal Factors:
Problems in the uterus or fallopian tubes can prevent the egg from traveling from the ovary to the uterus, or womb. If the egg does not travel, it can be harder to conceive naturally.
Surgery: Pelvic surgery can sometimes cause scarring or damage to the fallopian tubes. Cervical surgery can sometimes cause scarring or shortening of the cervix. The cervix is the neck of the uterus.
Submucosal fibroids: Benign or non-cancerous tumors occur in the muscular wall of the uterus. They can interfere with implantation or block the fallopian tube, preventing sperm from fertilizing the egg. Large submucosal uterine fibroids may make the uterus cavity bigger, increasing the distance the sperm has to travel.
Endometriosis: Cells that normally occur within the lining of the uterus start growing elsewhere in the body.
Previous sterilization treatment: In women who have chosen to have their fallopian tubes blocked, the process can be reversed, but the chances of becoming fertile again are not high.
Low sperm count: The man ejaculates a low number of sperm. A sperm count of under 15 million is considered low. Around one-third of couples have difficulty conceiving due to a low sperm count.
Low sperm mobility (motility): The sperm cannot “swim” as well as they should to reach the egg.
Abnormal sperm: The sperm may have an unusual shape, making it harder to move and fertilize an egg.If the sperm do not have the right shape or cannot travel rapidly and accurately towards the egg, conception may be difficult. Up to 2 percent of men are thought to have suboptimal sperm.
Abnormal semen may not be able to carry the sperm effectively.
In approximately 5% to 10% of couples trying to conceive, all of the above tests are normal and there is no apparent cause for infertility. In a much higher percentage of couples, only minor abnormalities are found that are not severe enough to result in infertility. In these cases, infertility is referred to as unexplained. Couples with unexplained infertility may have problems with egg quality, tubal function, or sperm function that are difficult to diagnose and/or treat. Fertility drugs and IUI have been used in couples with unexplained infertility with some success. If no pregnancy occurs within three to six treatment cycles, IVF may be recommended.