Infertility can be caused by problems with either the man's or woman's reproductive system, or both. Some conditions are hormonal in nature, and others are structural problems in the reproductive organs that require surgical repair.

Half of all couples tested for a cause of infertility are affected by a problem with the woman's fallopian tubes or uterus or her ability to ovulate. About one-third find that their infertility is caused by problems in the male reproductive tract. Some couples find that both partners have problems that are contributing to their infertility.