This babymed.com article discusses gay and lesbian pregnancy 0ptions--
The Surrogate
This option is utilized by gay and lesbian couples who wish not to carry their own child. The surrogate is impregnated with in-vitro fertilization with the sperm coming from a donor that is either a friend or a sperm bank. It's important to remember the legal ramifications. The surrogate agrees to carry the child and give it up for adoption to the “parents” after childbirth. There have been times when the birth mother chooses to keep the baby after birth and a legal battle ensues.
Donor SpermIn a lesbian relationship, donor sperm can be used to impregnate one or both parents. The use of in-vitro fertilization will often be used with the one of the lesbian couple being the biological parent of the baby.
Co-Parenting
Co-parenting occurs when a gay and lesbian couple raise a child together. One or both of the lesbians are impregnated with the sperm of the gay male parent. After birth, the couples choose to raise the child together as one family. The impregnation may occur through sexual intercourse or in-vitro fertilization.
AdoptionWhile there are several cases where gay and lesbian couples have successfully adopted children, the red tape and legal paths are stringent at best. The gay community often face the prejudices of those involved in the adoption process when trying to adopt a child.