A woman has spoken of her frustration at not being allowed to name her wife as a co-parent on their son's birth certificate, despite legislation being in place for two years to enable same-sex parents to be named on such documents.

Sarah Stone-McDevitt told RTÉ's Today with Sean O'Rourke that her three month-old child Lochlann's rights have been infringed by the fact that she could only put her name on the birth certificate and not her wife Ger's name too. 

Ms Stone-McDevitt said that essentially she is viewed as a single mother and she says her wife should not have to adopt the child she is rearing to be considered his parent.

She said the couple, who got married in Roscommon, have not benefitted from the provisions of the Family and Relationships Bill, which was enacted by the President in April 2015. 

She said that she had hoped the legislation would be fully in place to allow for a third column on the birth certificate next to 'Mother' and 'Father' for a 'Co-parent'. 

Ms Stone McDevitt stated that a heterosexual couple who undergo fertility treatment and have a baby using either/or donor sperm and egg are entitled to register themselves as the child's parents on the birth certificate.

However, she said if a homosexual couple also use donor sperm or egg they cannot register as parents at the birth registry office.

Ms Stone McDevitt said they must now wait two years for her wife to apply to be the child's legal guardian.

She said the issue causes unnecessary upset and concern for parents.