Artificial insemination is a method of inducing pregnancy without sexual intercourse by injecting sperm into the female genital tract. First introduced for livestock breeding purposes, artificial insemination of livestock allows proven sires to impregnate many females at low cost. It is now routinely used to help infertile couples. When sperm from the woman's husband is used, it is known as AIH (artificial insemination by the husband); if its is acquired from an unknown donor, it is termed AID (artificial insemination by a donor).