Infertility could be due to a number of reasons and often several factors contribute for infertility in a couple. These include:
Male factor infertility
This accounts for infertility in 25-40 % of couples. Problems with sperm include the abnormal shape of the sperm, the decreased number of sperm, or their inability to move effectively.
Problems related to ovulation or release of womans egg accounts for 25-30 % of infertility cases in couples. This could be due to hormonal causes or abnormalities in the ovaries such as polycystic ovary syndrome. These defects can be overcome using medications that stimulate ovulation.
Abnormality of the Fallopian tubes accounts for 20-30 % infertility cases among couples. Fallopian tubes connect the ovaries to the uterus. Tubal defects can be caused by infection, scarring from earlier surgery or a previous tubal ligation (tying of the tubes).
Endometriosis refers to the attachment of the uterine lining to various pelvic organs such as the ovaries, Fallopian tubes and sometimes even the intestines. This can cause scarring, pain, and affects the ability of the eggs to fertilize and create a pregnancy. This accounts for 5-10 % infertility in couples.
In about 10-20% couples there is no obvious cause of infertility. However, fertility treatments also are successful in these cases.