Artificial insemination (AI) is when sperm is placed into a female's uterus (intrauterine), or cervix (intracervical) using artificial means rather than by natural copulation. Modern techniques for artificial insemination were first developed for the dairy cattle industry to allow many cows to be impregnated with the sperm of a bull with traits for improved milk production.
Human artificial insemination
In humans artificial insemination is used as assisted reproductive technology primarily to treat infertility but is increasingly used to enable women without a male partner to produce children. The aim is to impregnate the woman by non-sexual insertion of sperm into the vagina or uterus.
The male partner of the woman undergoing artifical insemination produces a sperm sample usually by means of masturbation, although a special collection condom may also be used during intercourse. Alternatively, sperm provided by a sperm donor may be used if the woman's partner produces too few motile sperm, if he carries a genetic disorder, or if the woman has no male partner.
The man providing the sperm is usually advised not to ejaculate for two to three days before providing the sample in order to increase the sperm count.
A woman's menstrual cycle is closely observed, by tracking basal body temperature and changes in vaginal mucous, or using ovulation kits, ultrasounds or blood tests.
When using intra-uterine insemination (IUI), the sperm must immediately be “washed” in a laboratory and a chemical is added to the sample. The process of “washing” the sperm increases the chances of fertilization and removes any chemicals in the semen that may cause discomfort for the woman.
If sperm is provided by a sperm donor through a sperm bank, it will be frozen and quarantined for a particular period and the donor will be tested before and after production of the sample to ensure that he does not carry a transmissable disease. A chemical known as a cryoprotectant is added to the sperm to aid the freezing and thawing process. Further chemicals may be added which separate the most active sperm in the sample as well as extending or diluting the sample so that vials for a number of inseminations are produced.
When an ovum is released, semen provided by the woman's partner or by a donor is inserted into the female's vagina or uterus. Semen is occasionally inserted twice within a 'treatment cycle'. If the procedure is successful, the woman conceives and carries to term a baby as normal, making her both the genetic and gestational mother.
Artificial insemination has several variations both regarding the donor of the sperm and the techniques used.
Either sperm provided by the woman's husband (artificial insemination by husband, AIH) or sperm provided by a known or anonymous sperm donor (artificial insemination by donor, AID or DI) can be used.
Earlier, a popular form of artificial insemination was AIC, in which the sperm of the husband and a donor were mixed. The advantage of this procedure was that it could not be conclusively stated that the husband was not the biological father of the child. This was important in an age where artificial insemination was considered to be immoral and tantamount to adultery, with the resulting child being considered as illegitimate and having no inheritance rights. The popularity of AIC has reduced to almost nil for a number of reasons, including advances in genetic testing which make it fairly easy to identify the genetic father with a blood test, the advance of medical treatments for male infertility (such as ICSI), and the declining stigma of assisted reproductive technologies in general.
The easiest way to inseminate is by intracervical insemination (ICI), where semen is injected high into the cervix with a needle-less syringe. This process most closely replicates the way in which semen is depositied during normal copulation. However, more technical procedures may be used which increase the chances of conception. For example, 'washed semen', that is, semen from which certain chemicals have been removed, can be injected directly into a woman's uterus in a process called intrauterine insemination (IUI). IUI can furthermore be combined with intratubal insemination (ITI), into the Fallopian tube. This last procedure is generally regarded as having no beneficial effect compared with IUI ITI however, should not be confused with gamete intrafallopian transfer, where both eggs and sperm are mixed outside the woman's body and then inserted into the Fallopian tube where fertilization takes place. See also in vitro fertilisation (IVF) techniques which may involve the use of partner or donor sperm.
Artificial insemination has become a significant issue in recent years, particularly in debates revolving around same sex parenting, single mother parenting and surrogate parenting. Legal issues have arisen in cases where the gestational (and possibly genetic) mother decides to keep the child. Likewise, there have been debates over the rights of sperm donors.
Artificial insemination in livestock and pets
An artificial vagina used to collect semen from horses for use in artificial insemination
Artificial insemination is used in animals to propagate desirable characteristics of one male to many females or overcome breeding problems, particularly in the cases of horses, cattle, pigs, pedigree dogs, and honeybees. Semen is collected, extended, then cooled or frozen. It can be used on site or shipped to the female's location. The small plastic tube holding the frozen semen is referred to as a "straw". To allow the sperm to remain viable during the time before and after it is frozen, the semen is mixed with a solution containing glycerol or other cryoprotectants. An "extender" is a solution that allows the semen from a donor to impregnate more females by making insemination possible with fewer sperm. Antibiotics, such as streptomycin, are sometimes added to the sperm to control some venereal diseases.
Artificial insemination of farm animals is very common in today's agriculture industry in the developed world, especially for breeding dairy cattle (75% of all inseminations) and swine (up to 85% of all inseminations). It provides an economical means for a livestock grower to breed their herds with males having very desirable traits.