Three-parent babies are potential human offspring that will have three genetic parents. They are the subject of considerable controversy in the field of bioethics. Scientists have already produced pregnancies in which the fetuses contain DNA from three parents, but none have yet been brought to term. The process is currently prohibited in the United States, but is being actively researched in China.
The process of producing a three-parent baby involves taking the nucleus of one egg and inserting it into the cytoplasm of another egg which has had its nucleus removed, but still contains mitochondrial DNA, and then fertilizing the hybrid egg with a sperm. The purpose of the procedure is to remove a nucleus from a cell with defective mitochondria and place it in a donor cell with healthy mitochondria, which after fertilisation will contain a nucleus with genetic material from only the two parents. 
New York University researcher James Grifo, a critic of the American ban, has argued that society "would never have made the advances in treating infertility that we have if these bans had been imposed 10 years" earlier.
Opponents argue that scientists are "playing God" and that children with three genetic parents may suffer both psychological and physical damage. These critics include Alison Cook of Great Britain's Human Fertilisation and Embryology Authority, who argues that bans were "written to protect the welfare of the embryo and the child."
Film with expert speakers detailing the ethical debate surrounding 'Three Parent Babies' / 'Mitochondria Replacement': http://www.closeupresearch.com/mitochondria_replacement_ethical_considerations.html
- Short film with experts discussing the ethical / practical issues surrounding 'Three Parent Babies' / 'Mitochondria Replacement': http://www.closeupresearch.com/mitochondria_replacement_ethical_considerations.html
- Keim, Brandon, Three-Parent Children: Reality or Technicality?, Feb 5, 2008.
- Alleyne, Richard.'Three parent babies' take a step closer to reality, The Telegraph, Nov. 12, 2009.
- Randerson, James. Scientists seek to create 'three-parent' babies The New Scientist Oct. 19. 2004
- Frith, Maxine. Ban on scientists trying to create three-parent baby, The Independent, October 14, 2003
- Now, a three-parent baby
- Check E (November 2005). "Gene study raises fears for three-parent babies". Nature 438 (7064): 12. doi:10.1038/438012a. PMID 16267521.