FERTILITY AND INFERTILITY

respectively, the ability and inability of a human couple to conceive and reproduce. Fertility refers to the ability to become pregnant through normal sexual activity, and infertility is defined as the failure to conceive after one year of regular intercourse without contraception; approximately 80 percent of healthy fertile women are able to conceive during this period. Infertility can affect either the male or the female partner and can result from a number of causes. About one in every eight couples is infertile. Normal fertility depends on the production of a sufficient number of healthy, motile sperm by the male, delivery of those cells through open pathways into the vagina, successful passage of the sperm through the uterus and into the fallopian tubes, and penetration of a normal ovum (egg) by one of the sperm. A successful pregnancy also requires that the fertilized ovum subsequently become implanted in the lining of the female uterus. A defect at any one of these stages can result in a couple's infertility. Early efforts in the field of fertility management were aimed at preventing unwanted conception, and technological advances in the second half of the 20th century have made this a usually achievable goal. (See birth control.) The reverse situation, inability to conceive when desired, has been a problem throughout recorded history. Many kinds of infertility have responded to new medical management methods in the late 20th century, however.