This scientific breakthrough changed the possibilities for those who were unable to have children due to female infertility and for those at high risk for passing on hereditary disorders. As IVF developed, the procedures used in egg donation developed in parallel: the egg donor's eggs are now harvested from her ovaries in an outpatient surgical procedure and fertilized in the laboratory, the same procedure used on IVF patients. The resulting embryo or embryos are then transferred into the intended mother instead of into the woman who provided the egg. Donor oocytes thus give women a mechanism to become pregnant and give birth to a child that will be their biological child, but not their genetic child. In cases where the recipient's womb is absent or unable to carry a pregnancy, or in cases involving gay male couples, the embryos are implanted into a gestational surrogate, who carries the embryo to term, per an agreement with the future parents. The combination of egg donation and surrogacy has enabled gay men, including singer Elton John and his partner, to have biological children. Oocyte and embryo donation now account for approximately 18% of in vitro fertilization recorded births in the US.
