Infertility is defined as the inability to become pregnant after one year of trying. The cause of infertility may be with either the man or the woman or a combination of both partners. Female causes of infertility are often associated with problems with ovulation. The underlying reason may be premature ovarian failure (when the ovaries stop functioning prior to the onset of natural menopause); polycystic ovary syndrome (PCOS), when the ovaries do not regularly release an egg or do not release a viable egg; blocked fallopian tubes; physical problems with the uterine wall; or uterine fibroids. Male causes of infertility include the inability to have or sustain an erection, not having enough sperm or enough semen to carry the sperm to the egg, or having sperm that do not have the proper shape to move in the right way.