Two mums and one dad make one baby

The Baby made from two mothers and one father (1998).

After fertilisation, the developing embryo was implanted into the older woman's womb. The method is an alternative to egg donation for an older woman, where she lands up carrying a child that is not hers genetically. Six couples have undergone treatment at the Huntington Reproductive Centre in Los Angeles.

The procedure carries risks of genetic abnormalities as well as emotional risks for the children, whose identity may be called into question.  The technique is legal under British law and in many other nations, although it is illegal to manipulate the genes of a fertilised embryo.