used in surrogacy arrangements either by artificially inseminating the surrogate (known as traditional surrogacy) or by implanting in a surrogate embryos which have been created by using donor sperm together with eggs from a donor or from the 'commissioning female' (known as gestational surrogacy). Spare embryos from this process may be donated to other women or surrogates. Donor sperm may also be used for producing embryos with donor eggs which are then donated to a female who is not genetically related to the child she produces. Procedures of any kind, e.g., artificial insemination or IVF, using donor sperm to impregnate a female who is not the partner of, nor related to the male who provided the sperm, may be referred to as donor treatments. A Swedish study concluded that 94% of potential donors would be willing to donate to single women and 85% would be willing to donate to lesbian single women or lesbian couples. A review of two studies found that 50 to 68% of actual donors would donate for lesbian couples, and 40 to 64% would donate to single women. Provision A sperm donor may donate sperm privately or through a sperm bank, sperm agency, or other brokerage arrangement. Donations from private donors are most commonly carried out using artificial insemination. Generally, a male who provides sperm as a sperm donor gives up all legal and other rights over the biological children produced from his sperm. Private arrangements may permit some degree of co-parenting although this will not strictly be 'sperm donation', and the enforceability of those agreements varies by jurisdiction. Donors may or may not be paid, according to local laws and agreed arrangements. Even in unpaid arrangements, expenses are often reimbursed. Depending on local law and on private arrangements, men may donate anonymously or agree to provide identifying information to their offspring in the future. Private donations facilitated by an agency often use a "directed" donor, when a male directs that his sperm is to be used by a specific person. Non-anonymous donors are also called "known donors", "open donors" or "identity disclosure donors". A review of surveys among donors came to the results that the media and advertising are most efficient in attracting donors, and that the internet is becoming increasingly important in this purpose. Recruitment via couples with infertility problems in the social environment of the sperm donor does not seem to be important