Many couples find they're unable to conceive children. They're diagnosed as infertile when pregnancy isn't achieved after trying for one year (or six months if the woman is over age 35). Infertility affects more than 7 million people in the United States, and about 12 percent of women of childbearing age are considered infertile [source: Resolve].
Most infertility cases are treated with drug or hormone therapies or surgery. However, about 3 percent of cases require more advanced techniques, such as donor insemination or in vitro fertilization [source: American Society for Reproductive Medicine]. Some people in this small percentage do have successful pregnancies, while others choose to adopt and some become parents by partnering with a gestational carrier or a surrogate. A surrogate is a woman who carries a child for an individual or a couple -- usually called the intended parents.
Stories of surrogacy reach back to the Bible with the story of Abraham, his wife, Sarah, and her handmaiden, Hagar. In this story, Sarah finds she is unable to conceive and arranges for Abraham to impregnate Hagar, who goes on to conceive Ishmael. The first modern-day recorded surrogate agreement in the U.S. was made between a surrogate mother and a married couple in 1976 in Dearborn, Mich., drafted by a lawyer named Noel Keane. Keane subsequently went on to found the agency Surrogate Family Services, Inc. [source: Meinke].
The numbers of surrogates have been growing since 1976. In 2002, the number of surrogate births was estimated to be 550 [source: CDC]. And the Organization of Parents through Surrogacy (OPTS) show roughly 25,000 births through surrogate carriers in the U.S. since 1976 [source: USA Today].
But why would a woman choose to carry another couple's child? How do surrogate mothers become pregnant? Find out in the next section.