The normal reproduction process requires interaction between the female and male reproductive tracts. The woman ovulates and releases an egg from her ovaries to travel through the Fallopian tube to her uterus. The male produces sperm. Both egg and sperm normally meet in the woman Fallopian tube, where fertilization occurs. The embryo then implants in the uterus for further development. Infertility occurs when something in this pattern does not happen. The problem could be with the woman (female infertility), with the man (male infertility), or with both. Unknown factors cause infertility 10% of the time. For infertility with an unknown cause.