Insemination is the deliberate introduction of sperm into a female animal or plant for the purpose of impregnating or fertilizing the female for sexual reproduction. The sperm is introduced into the uterus of a mammal or the oviduct of an oviparous (egg-laying) animal.
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In mammals, insemination normally occurs during sexual intercourse, but insemination can take place in other ways, such as artificial insemination. Each form of insemination has legal, moral and interpersonal implications. Whether insemination takes place naturally or by artificial means, however, the pregnancy and the progress of it will be the same.
Insemination may be called in vivo fertilisation (from in vivo meaning "within the living") because an egg is fertilized inside the body, and is thus essentially the opposite of in vitro fertilisation.
In plants, the process of insemination is referred to as pollination.
Natural insemination
Insemination of a woman by sexual intercourse is technically referred to as "natural insemination" (NI) i.e. insemination by natural means. In humans, a woman is most commonly inseminated or impregnated by sexual intercourse with a male, who can be the woman's normal sexual partner or a sperm donor, ejaculating within a fertile woman's reproductive tract during sexual intercourse.
The incidence of natural insemination by sperm donor is usually a private matter, and may also carry greater risks than where sperm has been processed by a fertility center. However, advocates claim natural insemination generates higher pregnancy rates and a more 'natural' conception which does not involve the intervention and intrusion of third parties. Natural insemination by sperm donor will usually only take place during the woman's monthly fertile period to ensure the best chance of a pregnancy.
In most cultures, insemination by a male through sexual intercourse, whether the woman's husband, normal sex partner or not, is subject to social and sexual inhibitions and taboos, and has legal, moral and interpersonal implications.
Artificial insemination
Artificial insemination is the introduction of sperm into the reproductive tract of a female by means other than sexual intercourse for the purpose of impregnating the female.
In humans, artificial insemination can be used when a woman cannot, for any of a number of reasons, conceive by natural means, either by a sexual partner of her choice or by a sperm donor. Artificial insemination techniques available include intracervical insemination and intrauterine insemination. Artificial insemination using donor sperm is most commonly employed by lesbian couples, single women. and heterosexual couples when the male partner is suffering from male infertility. Compared with natural insemination, artificial insemination may be more invasive, and it may require professional assistance and medical expertise, which will have a higher cost.
In addition to situations where a woman's male partner suffers from male infertility, sperm from a woman's male partner can also be used to impregnate the woman artificially after the male partner has died or the partner has a genetic disorder. It may also be noted perhaps that the British Human Fertilisation and Embryology Authority warned in 2009 that babies impregnated artificially may have a 30% higher risk of genetic abnormality.
There are laws in some countries which restrict and regulate who can donate sperm and who is able to receive artificial insemination, and the consequences of such insemination. Subject to any regulations restricting who can obtain donor sperm, donor sperm is available to all women who, for whatever reason, want or need it. Some women living in a jurisdiction which does not permit artificial insemination in the circumstance in which she finds herself may travel to another jurisdiction (a 'fertility destination') which permits it. (See Sperm donation laws by country.)
Artificial insemination has been and continues to be commonly used in livestock breeding as an efficient way of increasing breeding.
Other forms of insemination
In various other animal species, sperm can be introduced into the female's reproductive tract by various means. For example, in some species of hemiptera sperm can be introduced violently by traumatic insemination, parenteral injection through the body wall. In some species of animals, sperm finds its way through the body wall when the spermatophore is left in contact with the female's skin, such as in the onychophora.