Infertility is defined clinically as not being able to achieve pregnancy after 1 year of having regular, unprotected intercourse, or after 6 months if the woman is older than 35 years of age. Many different medical conditions and other factors can contribute to fertility problems, and an individual case may have a single cause, several causes, or—in some cases—no identifiable cause.

​About 11% of women of reproductive age in the United States have experienced fertility problems. Many conditions can lead to infertility, like failure to ovulate, problems in menstrual cycle, structural problems of the reproductive system, infections, and endometriosis.